1. Observing Birds
What it’s all about
For most
children, birds are the most easily accessible wild animals. They provide a wonderful
opportunity for children to be inspired by watching nature. Observing birds allows children to engage in
studying and recording animal activities in a scientific manner. Bird watching provides children with
opportunities to study bird behaviour patterns, classification, adaptation and
ecology. For many children, birdwatching becomes a lifelong enriching
experience.
What you will need
1. Some basic household
materials for building a bird feeding station; perhaps some wood, if you like
to try some simple carpentry.
2. If possible (but not
essential), a pair of binoculars, a recording journal, and a bird book.
Getting started
A good time to start
this project is in the autumn when food gets scarce for the birds. If you feed the birds regularly, they will
make your home part of their daily circuit throughout the winter and summer.
Begin by helping your
child make a birdfeeder for your garden or veranda. You can make a feeder from a milk carton/jug, scraps of wood, or
other simple materials (see the Figure 1-1 and 1-2 for some simple design
ideas). Try to let your child do most of the work in making the feeder. You can
assist with the difficult parts, or intervene if the child asks for help. It is much better for your child to make a
feeder than for you to go out and buy one.
By involving your child in the design and building of the feeder, s/he
will have a greater interest in carrying out the project.
Hang the feeder from a
line in a place where it can easily be seen from the house/apartment. Be
careful to put it in a place where cats or other predators cannot get at
it. Have your child suggest ideas where
to place the feeder so that it is out of the reach of predators. Squirrels are sometimes a problem, too, and
you might need to put up squirrel barriers (once again, ask the child for
suggestions).
Commercial birdseed and
blocks of suet can be purchased from a pet or hardware store. Alternatively,
you can use kitchen scraps or stale bread crumbs. Try to get the child into the
habit of putting food out each day.
Starter activities
1. Give the child a
notebook to record observations. (Or make a notebook together.) This should be
stored safely and used like a diary, with each observation dated.
2. Observe the
activities at the feeder. Start with simple questions like “How many different
types of birds visit our feeder?” “How many of each type are there?”. Record these numbers each day. Using a bird
guidebook, try to identify the birds.
You can also get your child to do simple drawings of the birds that
visit. Point out that this is one way that scientists record data, and that
when recording scientific data, artwork need not be perfect. (A bird diary with
drawings can become a magical possession.)
3. Invite your child to
make observations at different times of the day. Review the daily entries with your child and ask him/her and if
there are differences in the numbers of birds that visit on different days, or
at different times of the day.
Encourage him/her to make educated guesses on the possible reasons for
any differences observed.
4. Note the weather at
the time of each observation, and invite your child to see whether s/he can see
any relationships between the types of birds that visit and the weather.
5. If you have friends
or relatives in different parts of the region, try to make this a shared
study. Compare notes on the types of
birds that visit in different geographic areas.
6. Have your child look
for specific bird behaviours such as bird squabbling. Do birds of the same type
squabble or fight? What are the outcomes of squabbles? Do birds of different
types squabble? Is the outcome always the same? Do birds ever hurt each other
during their squabbles? Is there different behaviour between adults and young
birds? Can you identify mating behaviour? Appeasement rather than hurting or
killing is often the outcome of animal conflicts: can you identify appeasement
behaviour?
Taking it further
1. Start experimenting:
a) Have your child place different types of foods in
piles or dishes to see which are preferred by each type of bird. Invite your child to compare food
preferences with the different types of beak and/or body size.
b) Make several feeders and put them at different heights
. Observe which feeder is the most
popular with each type of bird. Compare this preference with the type of feet
the birds have to see if there is any relationship between the type of feet and
the height of the feeders.
c) Record where the birds fly from to reach the feeder
(fence, bush etc.) Make a map showing these sites in the notebook and measure
distances. Then provide some new perches closer to the feeder (branches, posts
etc.) and see which are preferred.
d) Provide different types of feeders (different sizes,
openings, with or without perches, etc.) and observe which works best for each
type of bird.
2. Help your child to
photograph the different birds that visit.
Compare the photographs to the pictures in the birdbook. Look for similarities and differences.
3. Try recording bird
calls on an audiocassette. Invite your
child to match the bird calls with the various birds. Ask the child to try
imitating them to “call” birds. (Some stores stock inexpensive bird-calling
devices. You might want to consider
purchasing one.) Have your child experiment with these calls in the yard or
when you are going for a walk in the neighbourhood or in the park. See if the
calls make the birds pop up out of the bush to take a look at you.
4. Take a birdwatching
walk or hike. Early morning or late
afternoon is usually best for birdwatching. Also try looking at water birds on
the ocean or on a lake. All towns have birdwatching groups who welcome
newcomers and novices (especially children).
You might want to consider joining one.
5. Try making a bird nesting
box before the nesting season (generally the springtime). Birds like a small
(20x15x15cm) waterproof box placed up high where there is little likelihood of
disturbance by predators. Different sizes of entry hole are favoured by
different types of birds; try holes of 3, 4 and 5cm in diameter in different
boxes. Record which birds investigate the box, which make nests, and the dates
of these activities. If baby birds appear, count them and record their relative
successes in learning to fly, weight gain etc.
6. Try making a bird
bath. This is just a flat tray of any diameter containing less than 3cm of
water to avoid drowning. As with the other items, it should be place where cats
and other predators cannot get to it. Activities involve observing behaviours
in the water bath (drinking, bathing, grooming and so on.)
7. There are various
national scientific networks that actively solicit bird feeder data from
amateurs. Check out this internet website:
http://birdsource.cornell.edu/pwf/index.html
8. Buy your child bird
books or binoculars at gift-giving times.
2. Ecosystem in a Jar
What It’s All About:
Most people pass by
ponds and ditches unaware that they are teeming with miniature life. The
animals and plants that live in these small bodies of fresh water can easily be
brought indoors. A whole new world will be revealed to your family - a world of
interdependent creatures. Children are fascinated by these small pond creatures
and will happily learn to identify and study small freshwater animals and
plants for months.
An important biological
idea is revealed in an aquatic ecosystem that you can set up at home. Below,
you will find instructions on how to build such an ecosystem. This ecosystem is a miniature model of the
Earth in that it has only one source of energy - the Sun. On Earth, all the energy that plants use to
grow, reproduce and produce oxygen is supplied by the Sun. All life depends on
plant growth and the oxygen that plants produce. In a similar way, the plant
life in an aquatic ecosystem (both visible and microscopic) provides the energy
and oxygen needed by the rest of the living organisms in the ecosystem.
Many communities contain
small but rich pond ecosystems. Sadly, ponds are not valued much and are often
seen as muddy nuisances. Ponds are being drained and lost all around the world.
The reduction in the number of ponds is thought to be contributing to the
world-wide decrease in frogs, newts and salamanders (animals known as
amphibians.)
What you will need
• A large clean, clear jar such as a pickle
jar, with a tightly-fitting lid. An extra large plastic soda or water bottle is
also suitable, although a bit harder to fill.
• Water, bottom mud, and aquatic plants from a
freshwater pond habitat. You can collect the materials in ice cream
buckets and plastic bags. Scoop nets are useful for catching some of the larger
aquatic beetles.
• Magnifying glass, magnifying sheet or hand
lens.
• Journal or notebook for recording
observations.
Getting started
Look for a pond or ditch
the next time you and your child go for a walk. Forests and parks are good
places to start. Get close to the surface of the water to see if you can see
any organisms swimming around. You
might want to dip a plastic bag in the water and look at what you bring
up. A waterscope can be a useful tool
for looking a pond life (see Figure 2-1).
If you look closely, you should see small transparent creatures zooming
around that you and your child can bring home to create your “pond.” Most children will be thrilled at the idea.
Some will express distaste, but if you persist with the idea, most children
become fascinated by pond studies.
1.
Look closely at the water before you begin to build your ecosystem. The water from the pond will be full of tiny
creatures without backbones (called invertebrates), tiny plants (called
phytoplankton), and bacteria. The
bottom mud will be full of interesting larger animals, such as worms, leeches,
snails, flatworms, an assortment of insect larvae and eggs that are hidden in
the mud. If you use a magnifying glass
or magnifying sheet to look at the plants and animals, you will be able to see
greater detail. Encourage your child to identify as many organisms as possible
and to draw pictures in a pond notebook.
2.
Place 2 cm of bottom mud on the bottom of the jar. Then carefully pour the pond
water down the side of the jar, taking care to disturb the bottom mud as little
as possible. Fill the container about
3/4 full. You can add tap water if you
don’t have enough pond water. Get your
child to plant a small quantity of the aquatic plants in the mud bottom. (They
will grow rapidly.) Add a stick that is
long enough to protrude out of the water when it is leaning against the side
(see Figure 2.2). Ask your child to
guess why you are putting this in. (It’s to allow certain pond animals to crawl
out of the water.) You can either invite your child to write down their guesses
in their pond notebook or explain to them the purpose of the stick. Don’t be surprised if the water takes several
days to clear after you have created your miniature ecosystem.
3.
Seal the jar. This will prevent evaporation and ensure that this is a closed
ecosystem in which the plants and animals are in balance.
4.
Place the jar or aquarium in the shade; in the northern hemisphere an unshaded
north-facing window is ideal. Do not
put it in direct sunlight, as the heat from the sun will kill the animals. You
will need to monitor the light conditions carefully to ensure that the
ecosystem doesn’t overheat and that it is getting enough light. Try not to
disturb your ecosystem.
5.
Look at the ecosystem every day or every other day so that you can see the
changes in the populations of small invertebrates. Look at it at night too.
Try shining a flashlight in the side. Some animals get more active at
night.
6.
Use the magnifying glass to examine the organisms in the water. Leave the pond notebook by the aquarium and
make regular notes about the activities of the organisms. You and your child may choose to watch
together, or you may want to take turns observing and recording. Each week, measure and record how much the
plants are growing. Encourage your
child to think about what is happening in the ecosystem by asking questions
such as:
Where are the
animals found at different times of the day?
Where do they
go at night?
Who eats
whom?
How much do
the animals eat?
Do any new organisms appear?
Do the numbers of certain types of
organisms appear to be increasing or decreasing?
7.
Here are some of the organisms you may see (see Figure 2-3):
- water fleas (Daphnia) bobbing up and
down as they move. These aren’t
really fleas and they don’t bite. Look for increases and decreases in
their number.
- copepods (Cyclops) zooming around or
floating. The females will have
egg cases that look like baggy shorts.
- tiny black dots (seed shrimps) zooming
around.
- leeches swimming or looping along the glass
(They may only come out at night).
- white or red worms (Tubifex ) in the
mud waving their tails.
- transparent or green hydra attached to the
sides of the jars catching water fleas.
- snails gliding along the glass (Look for
tracks made by the teeth on their tongues as they eat the algae on the
glass).
- eggs laid on the glass or on the plants
(Watch for them to hatch)
- insect larvae chasing and capturing other
species.
8.
Watch for animals that change form. For example, insect larvae will turn into
adults (metamorphosis). If this
happens, be sure to release them outside, preferably near a pond.
9.
Look at the bottom mud as it develops an orange layer. This is a natural
phenomenon that occurs when bacteria that live in mud reproduce and increase in
numbers.
10.
If things go well, your ecosystem may survive for several years. You may wish to add new pond water from time
to time to boost the numbers of organisms. If you wish to dispose of your
ecosystem, return the components to the original pond or to a local watery
ditch.
11.
Things to watch out for:
•
overheating, which will cause everything to die and turn black and
stinky;
• takeover by anaerobic bacteria (those
that can live in low or no oxygen environments). This is unpredictable and happens occasionally despite all your
care and attention. All the components of the ecosystem will gradually turn
orange (and sometimes black) as the system becomes anaerobic (no oxygen) and
the other organisms die;
• walls of the jar become covered in black
or brown “stains.” These stains are actually colonies of tiny one-celled plants
called diatoms that tend to stick together on flat surfaces. You’ll need to scrape them off, or light
will no longer be able to get in and the other plants and animals will die,
causing the jar to go black.
Taking it further
1.
You may wish to check your local library for books that examine the life cycles
of the organisms.
2.
Challenge your child to see if she or he can figure out who eats whom and draw
a diagram that illustrates the feeding relationships (called the food web) for
his/her ecosystem.
3.
Investigate or map the distribution of ponds and streams in your neighbourhood
or nearby community.
Do they contain the same organisms as the
pond you used?
Do the ponds look healthy or polluted?
4.
Go on a guided tour or take a weekend workshop at a local nature reserve that
features freshwater habitats.
5.
Consider joining a volunteer community group that is working on the health of
local streams or ponds.
3. Pigeon Diversity
What’s it all about?
Pigeons are fairly
common birds in cities and towns around the world. A careful look at these
birds shows that pigeons have interesting plumage variations. This activity
encourages children to observe pigeons more carefully, to record the variations
they see and try to deduce the genetic makeup of the different birds. This is
also an introduction to the study of biological variation and genetic
diversity.
Pigeons are native to
Europe, where they were originally cliff-dwellers. This explains why they like
roosting in high spots on houses and skyscrapers. They have been extensively
bred by pigeon fanciers and pigeon racing hobbyists. Many of the variants you
will see are derived from birds that were escapees from captivity.
Background information
The characteristics of
all living things are determined by hereditary units called genes. Genes are
parts of chromosomes, long worm-like structures found in our cells. These long structures are made of a
threadlike substance called DNA. Genes are the functional regions along the
DNA. In most big organisms (like
ourselves), every cell in the body contains two complete sets of chromosomes,
hence all genes are in pairs.
Most of the variation in
plumage we see in city pigeons has occurred because of spontaneous changes in
the genes. These spontaneous changes
are referred to as mutations. Some of
the new appearances which originated as a result of mutations were considered
by pigeon fanciers to be particularly attractive. These pigeons were bred so that there would be more pigeons with
the same variations in plumage. At some
point, some of these pigeons escaped into the wild, where they began to breed
with other pigeons.
The original pigeon was
probably “blue” in colour (actually a steely-blue-grey), and had two prominent
“bars” on its wings.
Mutations from this original type have resulted in a
variety of types that now exist in populations. Some of the common mutant types
found in cities are (see Figure 3): checkered wings, red colour (actually a
pinkish-beige), grizzled pattern, and solid black. However, careful observation
will reveal many other, rarer types.
To keep track of normal
and mutant genes, scientists use an alphabetical naming system. Genes are
labelled with letters of the alphabet.
The same letter is used for each of the two genes in the pair.
Let’s use the pigeon
gene for blue colour as an example. The normal gene that determines blue colour
is represented by the capital letter “E”. The mutated gene that causes red is
represented by the small letter “e”.
Because the genes are always in pairs,
there are three possible gene combinations: EE, Ee and ee. In the Ee case, the
gene represented by the capital letter (E) “dominates” the other gene (e), so
pigeons of type Ee look blue exactly like those of type EE. Pigeons that have the ee combination are red in colour.
What’s needed
Journal for recording
observations. Binoculars are useful but not essential.
Getting started
If you see pigeons near
your house or in the park, pique the curiosity of your child by asking why
these birds always seem to hang around buildings. Ask them to imagine where pigeons might have lived before there
were buildings - or cities.
Invite your child to
notice the similarities and the differences between pigeons and to record these
differences by making notes or drawings in a notebook.
Help your child to analyse
the genetic makeup of two or more different-looking pigeons they have
observed. The information in the
“What’s it all about” section above,
and the coding system below should enable them to begin to describe the
genetic features they are observing:
Original Mutation
c = dark bars
on wings C = dark checker
marks on wings
E = bluish
colour e
= reddish pink colour
g = not
grizzled G =
grizzled (mottled with white spots)
s = not solid
black S =
solid black
Note that in
one case the original gene is dominant and represented by a capital letter
(that for blue), but in all other cases shown the mutations are dominant.
The complete
genetic makeup of any one pigeon type can be deduced as follows (a dash means
the gene can be either type):
Type Relevant
Genes
original
type (blue barred) cc EE gg ss
blue
checkered C-
EE gg ss
red
barred cc
ee gg ss
red
checkered C-
ee gg ss
grizzled cc EE
G- ss
solid
black cc EE gg S-
With your
child, visit a park over a number of days and count the numbers of each type of
pigeon in a flock. Each day, list the
different types of pigeons in order of commonness. Invite your child to explore whether the percentages are always
the same. You might want to consider
repeating this activity in another park or region. Are the same types of birds present and are the proportions
always the same?
Taking it further
Connect pigeon
variation with courting behaviour. Often male pigeons puff up their neck
feathers and strut around in front of the female as part of their courtship
behaviour. Suggest to your child that s/he follow one male bird that is doing
this. Is he making his advances to one female only or to any female? Invite
your child to investigate whether males tend to make advances towards females
of similar genetic type (eg blue with blue), or opposite genetic type (perhaps
blue with red). Alternatively, are pairings are more or less random?
4. Weed Watching
What’s it all about?
Weeds are viewed by
gardeners and farmers as a nuisance, but they are simply highly successful
plants that do very well in areas in which the soil has been disturbed. Most
weeds are plants introduced from another country; they succeed in competition
with native plant species. Many weeds have had an extremely negative impact on
natural ecosystems.
This activity will get
you and your child thinking about what weeds are about in your community, and
what factors enable these weeds to succeed. You will be exploring the annual
cycle of plants, how plants germinate and grow, and how they compete with one
another. The activity requires careful observation and recording over a period
of time. However it is an activity that can be carried out by looking at weeds
in your garden or on any vacant plot.
What’s needed
Notebook, pencil, ruler, string, wooden or plastic
strips to act as stakes. Possibly a plant identification book and a garden
sieve.
Getting started
Early in the spring when
the ground can be dug, invite your child to select a piece of ground for a weed
observation garden. Prepare a 1 meter x
1 meter piece of ground by clearing it of all visible plant material. It is important to get out all the roots,
stumps, bulbs, dead leaves that you can.
Dig up the earth to a depth of about 15 cm. If you happen to have a garden sieve, pass the soil through the
sieve to remove any remaining organic material. When you have finished, pat the
soil down gently so that it is flat.
Have your child divide
the square into smaller squares, using sticks, string, pieces of wood, etc. (see
Figure 4-1). Then, have him/her draw a
diagram of their garden plot in their journal
Now, sit back and wait
for things to grow. Have your child record the position of the various plants
that appear in his/her notebook. In
order to facilitate record keeping, suggest to the child that s/he give each
plant that appears a number. Every two
weeks s/he can draw a sketch of each of the plants so as to have a record the
changes that appear over time. Figure 4-2 shows one way of counting and
recording the number of plants using a colourful bar chart.
Encourage the child to record the height of each plant
when sketched, and to arrange the results to show which plants grow
fastest. One way to show these results
is to draw a chart of the changes in height over time. Discuss the best ways of
designing such a chart.
Taking it further
1. Encourage your child
to identify the plants as they mature and as new features appear. How long did
it take before your child was able to identify each of the plants? What features were particularly helpful in
the identification process?
2. Using a plant
identification book, try to determine which plants are native to your country
and which were introduced from another country.
3. Visit other yards,
gardens or parks to observe the types of weeds that are present. Engage your child in a discussion of which
types of environments particular plants appear to thrive in. As you and your child examine the plants
which seem to favour particular environments,
invite the child to identify which of each plant’s features might be key
to its ability to thrive in such an environment. Do these plants grow only in
areas disturbed by human activity or natural disturbances such as landslides?
4. Has your child found
areas where weeds seem to be competing with native plants? If so, is it
possible to tell which type is winning?
5. When the plants begin
to flower and produce seeds, estimate how many seeds each plant will produce.
Discuss the possible relationships between the number of seeds produced and the
success with which the weeds are able to grow in a particular environment. Try
to relate this to the origin of the weeds that grew in your plot. Encourage
your child to identify other features of the plants that might account for
their success as weeds.
5. Tree Charting
What’s it all about?
Trees not only
beautify a neighbourhood, but they produce the oxygen for us to breathe, reduce
atmospheric carbon dioxide produced from pollution, and provide homes for many
species of organisms, animals, plants and fungi. In this activity your child will learn to identify different
types of trees and recognize which ones are native and which were introduced to
your area from elsewhere. He/she will
also learn different methods of mapping trees and gain some basic knowledge
of tree biology.
What’s needed
Note book, a
tree identification book (available from most libraries), tape measure,
newspaper, knife, hand lens or magnifying glass, possibly a protractor.
Getting started
It is sometimes
difficult to decide whether a plant should be classified as a bush or shrub, or
whether it should be called a tree. This is something that can cause
difficulties for biologists, since young trees often look shrubby. For the purposes of this activity, tell your
child that a plant a will be called a tree if it has one main woody trunk with
relatively few branches near the bottom of the plant and many branches with
leaves higher up.
1. Begin by having your
child look closely at trees in a particular area. Your own neighbourhood or a small park or naturally treed area
will work well. Try to choose an area
that is not too big and daunting. Invite your child to go for a walk around the
neighbourhood or in the park to examine the various types of trees there are.
2. Trees are beautiful
and while most trees have some feature in common, each species has its own
special features. Engage your child in
a discussion of what appears to make one type (or species) of tree different from
another. Encourage your child to record in his/her your notebook a list of all
the tree features they notice. Gently
lead him/her to examine the colour and texture of the bark, height, amount of
branching, angle of branching, leaf shape, leaf arrangement, leaf colour,
flowers and fruits. A chart like the
one below may help to organize the observations:
bark
colour bark texture leaf shape leaf
arrangement leaf colour
1
2
3
You can also
look at branch pattern, shape of the crown of the tree (the mass of leafy
branches), the type of flowers, fruits, cones and anything else that enables a
tree to be distinguished from others.
3. Ask your child to
identify what he/she thinks are general categories into which we can classify
trees. It is not important that the categories be botanically correct. The main idea is for your child to start
thinking about the process of classification.
Encourage your child to
draw rough sketches to illustrate the different types of trees they have seen.
These sketches need not be detailed or finished works of art. They are merely a means of recording data.
Point out to your child
how important trees are, and suggest a further project to examine them more
closely.
4. Have your child draw
a map of the area and record where the various trees are found. If there are lots of one type of tree in a
particular area, encourage your child to show them as a group of trees on the
map. If there are lots of different kinds, you child might want to consider
developing a key or guide to indicate which type of tree is located where. Suggest to your child that he/she try out
the map with a friend or family member.
Can he/she find the trees indicated on the map?
If you are mapping an
open area such as a park, try a surveyor’s approach. Have the child make a
round disc of cardboard and mark it into 360 degrees (mark positions of 0, 10,
20, 30....360 degrees). Make a cardboard arrow the same length as diameter as
the disc. Use a thumbtack to attach the arrow and the disc onto the end of a
stick (at right angles to it) and drive the stick into the ground (Figure 5-1).
For each tree to be mapped, look across the now horizontal disc and record the
position of the tree in degrees. Now walk to the tree and record how far it is
in paces. Hence, for each tree, you have the angle it is seen at and its
distance. These measurements can easily be converted into a map on paper.
5. Have your child begin to look more closely
at a tree that s/he finds particularly interesting or beautiful. Encourage him/her to focus on the general
shape of the tree and how the branches are distributed. Have him/her note the
shape and size of the leaves and fruits. Are the leaves are in pairs opposite
each other, or do they alternate up the stem?
Have your child record his/her observations by drawing a leaf in the
recording notebook. If drawing the leaf
is too difficult, encourage him/her to do a leaf rubbing by placing a piece of
paper over the leaf and rubbing a soft pencil across the paper to bring out the
leaf shape.
6. Encourage your child to observe how the tree
changes over time. Do the leaves change colour? change size? Do the leaves fall off? Do any remain behind? Some types of trees keep their leaves all
year long (evergreen trees) and others drop their leaves in the fall (deciduous
trees). Conifers (cone-bearing trees) are mostly evergreen (for example
Christmas trees). Most deciduous trees have broad leaves, whereas conifers have
narrow needle-like or scale-like leaves.
Taking it further
1. Buy or check out of
the library a tree identification book with lots of pictures. Look at the
pictures and try to decide if any of the illustrations resemble the trees in
your community. There is no need to learn botanical names for all the trees in
your study area. Identifying even a few will be good practice in careful
observation and comparison.
2. Compare the trees in
your area with another area - perhaps an area far away (your summer holiday
site?). What are some reasons for the differences between the trees in
different locations?
3. Try to find out what
trees were growing on your town block before buildings were built. Think about
and discuss how you might be able to figure this out. (Try a comparison with
nearby natural areas for clues).
4. Trees have their very
own animal communities. Begin to look for the organisms that live on trees. Try
to go beyond birds and squirrels. Scrape the surface of the bark and collect
the scrapings on a piece of newspaper and examine them closely for tiny
plants and animals. Record any plants or animals you see. A hand lens or
magnifying glass is useful for this.
Ask your child to speculate how these organisms obtain their nutrition.
Look carefully at the undersides of leaves and branches to find insects. Try
“beating” the branches over a sheet of newspaper or plastic and see what
insects fall out. (This is the time-honoured method used by all professionals
and amateurs who study insects). Encourage your child to draw some of the
insects in the recording journal.
5. Tree reproduction is
interesting. Trees grow from
seeds. Questions that you might want to
investigate with your child include: What do the seeds of a particular type of
tree look like? Where are they found on the tree? Are the seeds present all year round or only at certain times?
How are they dispersed (by animals? by wind?) Big seeds such as nuts, acorns
etc. are easy for a child to handle and grow.
6. Try measuring the
heights of some trees. It’s not necessary to have an extra tall ladder or
mechanical device to do this. On a sunny day place a stick in the ground and
measure its height and the length of its shadow. Now measure the length of the
shadow of a tree. The height of the tree can be calculated as follows:
Height of tree = height
of stick multiplied by length of the tree shadow, all divided by the length of
the stick’s shadow.
Mathematically, this is
true because in triangles with the same angles (similar triangles), the ratio
of any two sides is always constant - see Figure 5-2.
Another easy way to
measure a tree is to stand 50-100 meters away from the tree and have a friend
or parent of known height stand under the tree. Hold up the stick at arm’s
length and line up the friend with the stick and make a mark on the stick (see
Figure 5-3). Next do a sighting on the height of the tree and mark this on the
stick, then the width, trunk and any other measurement needed. Then simply do
the following type of calculation, which basically asks how many “friend
lengths” the tree is, and multiplies by the friend’s height.
size of tree
on the stick divided by size of friend on stick, all multiplied by size of
friend.
Example:
Height of
friend = 2 metres.
Size of tree
on stick = 24 cm
Size of
friend on stick = 3 cm
Therefore
height of tree = (24/3) x 2
metres = 8 x 2 = 16 metres
7. Spot the “top ten”
trees of your area (measured in terms of most numerous or most ground cover).
6. Measuring Plant Growth
What’s it all about?
Plant growth is
important in farming, horticulture and forestry, all key elements of the
economy. This activity invites you to examine the miracle of plant growth in a
new way that can stimulate interest in plant biology.
What’s needed
A growing plant. In the
home, a bulb is good material to study (Amaryllis is the most spectacular, but
any will do). Broad beans (or any beans) are also good and fast-growing.
However any fast-growing house plant will do. If you are starting your own
plant, you need seeds, a pot, some potting soil, and a location near a window
where the plant can get sunlight. India ink, a thin pen nib or brush, (or a
thin permanent magic marker), a ruler.
Getting started
The following steps deal
with Amaryllis and broad beans, but the same approach can be applied to any
plant.
1. Amaryllis: Plant the
bulb in soil, keep the soil moist, and place it in a warm place with light.
Begin the project once the flower bud has emerged and the stalk is about 5 cm
long (see Figure 6-1).
2. Bean: Roll up some paper towels or other
absorbent paper and place inside a jar containing an inch or two of water.
Place the bean down the side, wedged between the wet paper and the glass, but
not submerged (see Figure 6-2). Top up water as it evaporates and never let it
run dry. Once the bean has put out its stalk and leaf, allow the stalk to grow
about 3 cm and begin the project. Keep the paper wet and keep turning the plant
to avoid it leaning over into the light too far. (Alternatively, you might want
to monitor the movement of the shoot throughout the day, which makes an
interesting study in itself.)
HINT: Plant an extra bulb or bean or two if you
can. When doing any activity where you study living things it is always a good
idea to study more than one.
3. Keep track of how your plant grows. To do
this you will need to mark various parts of the plant (stem, leaves, even roots
in the beans) with lines spaced evenly apart, say 1mm apart (see Figure 6-3).
This takes a steady hand, but is not too hard to do.
4. Observe carefully and
record the growth changes in a notebook or journal. As the plant grows, watch
what happens to the lines, and record the results with sketches and
measurements of the distances between the lines.
5. Explain your observations.
What parts of the plant
show no growth? Which part shows the fastest growth? Is growth occurring along
the long axis (length) of the plant or across the width of the plant, or both?
Calculate the rate of growth in the various marked off regions (that is, how
many millimetres does a part grow per day?).
Are your answers to these questions the same for each of your plants (assuming
you planted more than one). If not, why
not?
Taking it further
The same approach can be
used in garden plants, although because rain might wash off the ink, you might
need to use paint or nail varnish to mark the lines on your plants. Experiment
with different types of plants. The quickest and most interesting results will
be obtained in spring and early summer when the plants are showing their
fastest growth. Compare the growth speed of different plants. Which are the
fastest? What types of plants are the fastest?
7. Making a Plant Collection
What’s it all about?
Botany (the study of
plants) is a fascinating hobby for children, and if their interest is piqued
when young, studying plants can provide a lifetime of pleasure. In this
activity the child constructs a plant press and uses it to prepare a collection
of local plants. This activity is an introduction to plant biodiversity in the
community, a key element in awareness of the environment and in conservation
issues. The activity also gives practice in recording botanical information and
plant identification and provides an opportunity to gain skill in plant
illustration.
What’s needed
- two sheets of plywood either 6 mm or 9 mm
in thickness and about 30 cm square
- up to ten sheets of corrugated cardboard
the same size as the boards (old grocery boxes are fine for this)
- up to twenty sheets of newspaper the same
size as the boards (this is an excellent opportunity to recycle newspaper)
- four 4 or 6” stovebolts with wingnuts on
them, eight washers, a drill and bit of diameter slightly larger than the
stovebolts, (a couple of old large belts work fine for securing the boards
if you don’t have bolts and wingnuts)
- white paper
- transparent tape
- possibly a plant identification book.
Getting started
1. Make the press - see
Figure 7-1.
2. Take a
walk, bike ride or drive to the nearest natural area and collect up to 10
healthy specimens of plants, with flowers if it is the flowering season, and
roots if they are not too big. Remember the specimen has to fit in the press
you have made. Wash any dirt from the plants and blot dry. Create a collector’s notebook and record the
date and the site where the plant was found, as well as a brief description
about what the plant was like.
Two
environmental and legal cautions:
• it is
illegal to pick plants in parks or conservation areas
• use common
sense and do not pick any plant that seems to be rare.
3. Set up your plant press. Place the plants between two sheets of
newspaper and stack as follows:
wood / cardboard /
newspaper / plant / newspaper / cardboard - and so on.
Don’t forget to create a
system for recognizing your plants later -- jot a number on a bit of paper or
on the newsprint and record this number next to your notes in your
notebook. This will make identification
much easier when you open your press later on.
Put the bolts on and
tighten the wingnuts so that the plants are firmly pressed between the sheets.
Don’t overtighten - this will bend or break the boards. If you are using straps
or belts, pull them tight around the entire sandwich of boards and plants.
4. Allow the press to dry for a few weeks in a
dry place. Have a look to see how the drying and flattening is progressing.
When the plants are dry, remove them and begin the cycle again with new plants,
if desired.
5. Mount the dried,
pressed plants on the sheets of white paper, sticking them down with small
pieces of scotch tape. Don’t forget to write down the number of your plant on
the corner of the paper.
6. Identify your plants. Now is when your system of recording comes
in handy. Refer to your number and the
notes in your collectors notebook and try to identify your plant (if you
haven’t already done so). Write the
names of the plants on the paper alongside the pressed plant. Also write the
date and collection site.
7. The plants can be
stored in between two large sheets of cardboard tied up with string. Or they
can be made into a scrapbook.
Taking it further
1. Take your plant press
on holiday and make a collection of holiday plants. In most countries, if you
go abroad it is legal to bring back dry plant material if there is no dirt on
it. Dirt may contain insects or other creatures that may harm local plants so
make sure your plants are completely dry, pressed, and clear of any soil.
Compare the holiday plants with the local plants.
2. Join a club and find
out more about plants. Local natural history or nature clubs often hold plant
hikes; this is a natural extension if your child shows some interest in finding
out more about plants.
3. Make greeting cards
using dried flowers arranged in pleasing patterns. The plant names could be
written on the back of the card.
4. Go to the seashore at
low tide and sample the marine plants, (seaweeds). Look for small specimens, as large ones are difficult to dry and
store. (Hint: the tiniest ones are very beautiful and delicate and live on the
rocks in tidepools.) The drying process is the same as described above, but you
will need to change your newspapers more often to help in the drying process
(seaweed starts wetter, and takes longer to dry).
8. How the Human Body Grows
What’s it all about?
Growth is a key element
in the maturation of any organism, and human growth is an easily studied and
interesting type of growth for children to explore. This activity involves
measuring family members and correlating the measurements with their age and
gender. A program of measurement carried over a long time period can show how
sizes and proportions change with time.
What’s needed
Tape measure, pencil,
notebook, perhaps some graph paper (or any paper marked with squares).
Getting started
Many body measurements
can be heavily dependent on dietary quality and quantity. In doing a growth study it is best to
measure body parts that aren’t directly influenced by what you eat. The measurements below are chosen to be
relatively independent of diet.
1. Create a data table
in your notebook or journal. For each family member measure record the
following information:
- height
- length of torso from shoulder to groin
- circumference of head just above the ears
- length of hand
- width of hand
- length of middle finger
- length of arm from armpit to wrist
- length of upper arm
- length of lower arm
- length of inner side of leg (measure
standing)
- length of thigh (knee to groin)
- length of calf
- length of foot
- width of foot at ball of foot.
2. Look for
relationships between each measurement and the age and gender of different
family members. To do this, first graph each measurement in relation to
age. Do
the points in your graph all lie on a single, straight line? If the answer is
yes, then growth is a constant value over time. If not, then the speed of
growth must be different at different ages. Repeat this activity, this time
graphing measurements in relation to gender.
3. Calculate some ratios
of measurements and see how these vary with age. For example, hand length might
be 20cm and hand width 5cm, so the ratio of the two would be 20 divided by 5
which equals 4. Choose two measurements
and calculate the ratio for the various family members. Then graph these ratios against age in the
same way as you did in procedure 2 above.
Do you notice any patterns?
4. Make measurements of
children at 3 monthly intervals. Graph these against age. At which age is
growth most rapid? Which ratios change the most?
9. Mushroom spore prints and beyond
What’s it about?
Fungi are crucial
components of the environment, as they are nature’s recyclers. In the ecosystem, they promote the decay and
rot of dead organisms, thereby returning the nutrients to the environment so
that they can be reused by other organisms. (Imagine what would happen if this
didn’t occur - all the dead plants and animals would accumulate!) The type of
fungus that most of us are familiar with is the mushroom. Mushrooms appear either on the surface of
the ground or as plate-like protrusions or “brackets” growing on the bark of
trees. Fearing that they are dangerous, poisonous or slimy, children are
sometimes frightened by fungi. A few fungi are poisonous, however handling
these is not dangerous if the hands are washed afterwards. (Never eat
any type of wild mushrooms – even those people tell you are edible. Even
“experts” are sometimes fooled by them.)
Mushrooms (and other
types of fungi) reproduce by means of spores; they don’t produce seeds like
flowering plants. Spores are reproductive cells that can grow if they fall on
the right surface, and become a new fungus.
This activity begins by
making a collection of spore prints from mushrooms. Spore prints are used by
experts to help identify the species of a mushroom. The prints can also be kept
as a permanent record in your notebook or scrapbook.
What’s needed
White and black
construction paper. Notebook and pencil. Perhaps a fungus identification book.
Kitchen dishes or plastic tubs. Possibly some hair spray or art spray.
Getting started
1. Find some mushrooms.
Mushrooms generally appear in spring and fall, when the weather is damp. So it is best to go mushroom hunting during
these two seasons. Take a hike to an empty lot, in a forest or wood near your
home. Collect about 20 mushrooms in a paper
bag or box.
2. Collect some data
about your mushrooms. Assign each specimen a number and make a quick sketch
showing its size, shape and colour. Then record the date and place where you
collected each specimen.
3. At home prepare your
spore prints. Cut off the caps (Figure 9-1). Note that underneath the caps are
radial membranes called the gills. The spores are produced on the gills. Pull
away any tissue to expose the gills fully, and then place the cap gills-down on
the white or the black paper. Place a dish, cup or plastic tub upside down over
the cap to prevent air currents from disturbing the spore drop. Leave the caps
on the paper overnight and inspect the next day. If there is no spore print,
leave them longer, as necessary. If you have no success the first day on one
colour paper, repeat the next day with the other colour - they might show up
better. If you have success, remove the dish immediately, label the spore
prints and leave them for another day to dry off.
4. Preserve your spore prints.
Apply hair spray or art spray carefully (if available) to attach your spores to
the paper. To avoid changing the
arrangement of spores, apply spray from
about 30 cm away, letting it fall gently on the prints. Label the spore prints
with the specimen number. In the notebook, next to the specimen number and
sketch, stick in the spore print. Cover
with wax paper if spray is not used.
Taking it further
1. Make collections at
different times of year, and from different places. Compare with your first
collection.
2. Try to identify some
of the mushrooms using a mushroom book specific for your area.
3. Look for evidence in
the soil that will show you more about how mushrooms grow. Mushrooms don’t have
roots like green plants. Explore the soil around the base of mushrooms and try
to locate the whitish threads that are the underground part of the fungi and
which absorb nutrients from the soil.
4. Try recording fungal
diversity in different places in your neighbourhood:
• Compare fields with forest. Do you
notice any difference in the diversity? In the forest, many of the mushrooms
are living in symbiosis with the roots of trees - these are called mycorrhyzal
fungi - so they tend to be bigger and more numerous than the mushrooms in
fields, which are mostly saprophytic, breaking down dead plant and animal
material to obtain nutrients.
• Compare mushrooms growing near or under
broadleaf trees with those under evergreen trees (you will probably see more
under the former).
• Bracket fungi grow on tree trunks,
looking like protruding shelves. Compare bracket fungi with others. Some
bracket fungi decay the non-living heartwood, some are parasitic on the living
sapwood. Are they bigger or smaller than soil fungi? Do they have stems?
Speculate why or why not? What are some other differences?
• Try poking around close to the ground
for small or unusual fungi. Remove the leaf litter - you might see small “cup
fungi,” small mushrooms, and possibly the whitish threads that fungi are made
from.
• Look for jelly fungi, which grow on
dead tree stumps, logs or fences (they look like pieces of yellow or whitish
jelly), and coral fungi, which grow on the ground.
Make an
assessment of fungal diversity in your area studied.
10. Observing and recording animal behaviour
What’s it all about?
Someone once said
“Science is seeing what everyone else has seen, but thinking what nobody else
has thought.” In this activity, we try out this notion on the behaviour of
animals. Everyone has seen animals behave, but here we try to record
scientifically exactly what this behaviour is
and how much time they spend on various activities. Some of these
activities are innate whereas others are learned. Behaviour is just as
important a component of an animal’s characteristics as its appearance. Hence,
understanding behaviour is a key to understanding the needs of various animals
to survive in their natural and human-made habitats.
The activity involves
careful observation, making choices about categorizing the activities the
animal is engaged in, and recording the activities for future analysis.
What’s needed
Pencil, notebook, timer
(watch, stop watch, clock - whatever timing device is available; if you have no
timing device you can count seconds by saying “one crocodile, two crocodile
three crocodile”, etc.)
Getting started
1 First choose what
animal in your community you would like to study. Household pets are a good
place to start. Common animals like squirrels, birds and insects also make
interesting subjects.
2. Have a preliminary
look at what your chosen animal does and decide what categories of behaviour
would make up the daytime activities of the animal in question. (For examples
see the list below] This doesn’t have to be an exhaustive list; you can always
expand on it later if necessary.
3. Draw up a chart in
your notebook showing the categories of behaviour.
4. Spend some time
observing the animal closely and recording the amount of time it spends on each
activity. Try to stay at a distance from the animal so as not to disturb its
natural behaviours - in other words, spy on it unobserved if possible. An
example of your observations might be:
“activity A, 10 seconds,
then activity B, 30 seconds, then activity A, 15 seconds, then activity C, 20
seconds........” and so on.
5. Enter these on the
chart and at the end of the observation period, calculate total time spent on
each activity.
6. Repeat at different
times of day and different seasons for the same animal, and compare different
animals.
7. Do some further
analysis and thinking about of the behaviours you see to learn more about the
particular individual and/or species.
Some activity categories
to guide your analysis for specific animals:
Squirrel Activities
·
Resting
·
Obtaining food
·
Grooming
·
Territorial behaviour (chasing, threatening, fighting)
·
Mating
·
Communication (calling, tail waving etc.)
Bird Activities (see Activity 1)
- Resting
- Obtaining food
- Grooming
- Nest building
- Territorial behaviour (chasing,
threatening, fighting)
- Mating
- Food preferences
- Communication (calling, displaying,
posturing)
Cat/dog Activities
- Grooming
- Obtaining food
- Resting
- Aggression
- Territorial behaviour (barking, chasing,
etc.)
- Mating
- Playing
- Communication (calling, tail wagging,
sniffing)
Bee Activities
- Obtaining food (from flowers)
- Travel
- Resting
- Communication
- Time on flowers of plant species A, species
B, etc.
- Time on flower 1
- Time on flower 2, etc.
- Time on plant 1, plant 2 of species A
- Time spent within 1 meter radius of a
particular plant or object
- General direction of journey
- How were the times of a second bee
influenced by the times of the first?
Additional Bee/Wasp
Study Activities
Make artificial flowers
from different coloured paper. In the middle of one put a soda bottle cap (or
other small container) full of sugar water or honey. Wait for one bee to find
it, then time how long it takes for the number of bees on the sugar to
rise to 2, 3, 4 etc. Once the sugar has been well and truly found, move the
sugar cap and mix up the positions of the coloured flowers. See which one the
bees will go to.
Fish Activities
- Obtaining food
- Resting
- Communication
- Aggression
- Just swimming
- How many times does the fish pass a piece
of tape stuck on the side of the tank?
- How long does it spend at the bottom,
middle, top of the tank? (Use tape to divide the tank).
·
Is behaviour
affected by time of day? For example, how do these times change at different
time of day?
·
Is behaviour
affected by the weather? For example, how do these times change in different
weather conditions?
- How do activities change in different
degrees of lightness/darkness?
·
Can the fish
anticipate feeding time (can you prove this with your records?) Can you train a
fish into a feeding response using a bell or other signal?
Taking it further
1. Try doing your animal
behaviour study in varied locations.
The same types of observations and measurements are fun and interesting
to do at the zoo or aquarium.
2. Human beings are
animals too. Try the same kind of
observations on people, at the beach, in the park, in the shopping centre etc. If
you decide to study people, remember it is important to be sensitive and
polite; staring directly at people will make them uncomfortable -- be
unobtrusive and discreet.
3. Try Activity 1, also
about animal behaviour.
11. Snail population biology
What’s it all about?
Snails are commonly
encountered animals in most parts of the world. This activity asks children to
take a new look at snails, examine their unique structure and habits, and
perform some simple analyses in basic population biology and general biology.
In some snail populations there might be genetic variation between the
snails. This can be assessed as a type
of biological diversity.
What’s needed
Several collection
vessels such as plastic tubs and lids with small holes for air; one litre
plastic soda bottle; sticky tape; marking pen; several small pots of hobby
paint (enamel or acrylic), coloured nail varnish or other waterproof paint;
notebook and pencil.
Getting started
1. Determining
distribution.
Look for snails in your
garden or any other site in your neighbourhood. Snails come out mainly at
night, so this would be a good time to look for snails on the move. (Use a
flashlight). In the daytime, they often come out after a rain storm. Look on
the branches of bushes, trees and other plants. Snails often hide down in long
grass or rest high in the branches of shrubs.
Try to be systematic in
your collecting. Record the number and
types of snails you find in each place (e.g. each bush). Draw a map of the collection site and use it
to record where you found the snails. All the snails you find will be called
collectively “sample 1”.
2. Estimating
population size
Mark all the snails you
have collected in the following way (see Figure 11-1). Dry the shells with a
cloth or paper towel and put one or more small dots of coloured paint on the
snail shell, well away from the shell opening. Alternatively, you could paint
numbers. Let the paint dry (the paint types suggested above are fast drying).
Release the snails and record where they were released. They should be released
randomly over the area.
After one week collect
the same number of snails you collected previously – call this sample 2. If you
find marked snails, record their location and compare this location with that
of the previous week. The aim is to see
if the snails return home to a specific site.
Add up the total number
of marked snails in sample 2. You can estimate the total population size of
snails in a area by looking at the proportion of marked snails in the second
collection. If the second time you found that 1/3 of the snails are marked,
then the total population is
collection sample size (say 100) x 3 = 300
You might be surprised
by the answer you obtain!
(This is called a mark and recapture
experiment, a procedure used extensively in population biology.)
Finally, write a short
summary of your studies on the total population size, site preferences, and
mobility of snails. Ask your neighbours if they have seen any marked snails.
How far do the snails move?
Taking it further
- Make a snail habitat in a plastic bottle
(see Figure 11-2). Put about five snails in the bottle. Place the bottle in a shady place in
the garden or in a garage or shed (not indoors). Record the snails’
activities during the day and night. Place pieces of vegetable in the
bottle (carrots, lettuce, potato etc.) Observe and describe how snails
eat. Record which vegetables they eat. Assess feeding preferences.
- Did you see different shell patterns and/or
colours in different snails? You might be looking at the snail Cepaea
("see-pay-a"). These patterns are genetically determined. In
their original territory (Europe), there is evidence that these patterns
confer a type of camouflage against predators (birds mainly) and specific
patterns give protection in specific habitats. Test this idea by measuring
the proportion of specific patterns collected in different habitats. This
would be best done in several natural settings, eg. reeds, grass, shrubs,
etc., or wherever you can find the snails.
3. Watch a snail in
action to learn about how it moves. Measure the speeds at which snails move.
Mark where a snail starts moving, time two minutes and measure distance
covered. Calculate average speed in mm per minute. Do this on different days
when the air temperature is different and look for correlation of speed with
temperature. Find the snail individual speed record holder. Have snail races.
(They love to crawl upwards, so position them at the bottom of a sheet of
plastic or wood and tilt it vertically.) Put snails on their backs and record
how long it takes for them to flip over. Are the fastest flippers also the
fastest crawlers?
4. Can snails crawl over
sharp objects? Try broken egg shells
and razor edges. (Get a small wooden block. Ask your parents to tack razor blades around the edge to make an
enclosure. Place snails in middle and watch what they do: can they crawl over
the sharp edges of the razors?)
6. How strong are
snails? Devise a sled out of a plastic lid. Attach it to the snail’s shell with
tape (Figure 11-3). Add small stones one at a time to the sled and see what the
maximum weight is that snails can move.
Weigh the stones to get a precise measure. Find the strongest snail.
7. Snail territoriality.
Put out an upside-down flower pot and prop it up a bit with a stone so that
snails can get in. Snails go out and eat mainly at night, and will find a
hiding place before daytime. Check to see if snails have used your hiding
place. Mark them with numbers and put them back in the pot. Check again the
next morning to see if you have the same or different snails. Explain the
results.
12. Fungal Succession on Manure
What's it all about?
Fungi are the
decomposers of nature. They break down dead plants and animals and various
kinds of solid and liquid animal wastes, returning the nutrients into the
ecosystem. This activity focuses on
manure fungi, and shows how they break down horse manure.
A number of different
fungi will be observed on the manure, in a precise order. This precise sequence
is caused by two things: first, different fungi grow at different speeds, and
second, one fungus can prepare the way for another. When one organism, merely
by living in one place, prepares the conditions that make it possible for
another organism to live there later, and the second organism prepares the way
for a third, and so on, the process is called ecological succession.
Succession is a well established general ecological phenomenon observable in
many settings.
In this activity, the
organisms are fungi living on horse manure. Fungal spores on the grass eaten by
a horse survive the journey through its body, and then germinate and grow on
the manure.
The activity is an
introduction to the ecological principle of succession, and to the subject of
mycology (the scientific study of fungi).
What’s needed
An extra-large clear
disposable plastic bottle such as a 1 or 2 litre soda or water bottle. A large
pickle jar is also suitable. A manure collection bag (supermarket bags are fine
for this). Horse manure from a horse
feeding in pasture (a field) or from hay.
Some clear tape. Notebook and pencil.
Getting started
1. Collect some fresh
manure - enough to fill the bottom third of your clear bottle.
2. Cut the top off the
bottle so that the manure can be put inside. Then use the tape to connect the
top back on (it doesn't have to be a perfect seal). Poke a few 1mm holes in the
upper part of the bottle.
3. Place the bottle in
the shade to allow the fungi time to grow. In the summer, put it outside the
house, and in the winter put it inside - a window sill on the north side is
about right. The bottle must be in the light for the daylight hours. After
putting the manure in the bottle there will not be any appreciable odour from
it, however make sure no pets or other animals can knock it over.
4. Watch what happens to
the manure. Fungi will start appearing after a few days. Record and describe
any and all fungal growth. Record the
date at which growth of one fungal type begins and ends. Draw the fungi that
grow.
5. Summarize the entire
succession of fungi from beginning to end.
Taking it further
1. Was the fungal
succession in your first experiment just a chance thing? Or was it a
biologically inevitable sequence? Explore these questions by repeating the
experiment with another sample of manure from the same horse, a different
horse, the same field, a different field.
2. Try dung from
rabbits, sheep or deer, and compare the fungi that grow.
3. Compare the results
in all your trials. If you find the same sequence in all cases, make a record
of this sequence.
4. You can experiment
further by changing the conditions in your bottle.
• Try adding water so that the manure is partially (not
fully) submerged.
•
Try adding a table spoonful of vinegar mixed with water, or a spoonful of
baking soda in water.
• Try putting the manure in the dark.
• Try higher and lower temperatures.
5. From the library
obtain some books on fungi and see if you can find the scientific names of
fungi similar to the ones you observed on the manure. If you are unsure of a
specific case, a statement such as "Looks like species X" is quite
acceptable.
13. Tree Girths - a population study
What’s it all about?
This activity asks your
child to document the sizes of trees in a particular area of his/her choice.
Through an analysis of tree size, your child will begin to investigate the
ecology and structure of tree populations, and will get an introduction to
statistics. There is also a game
element that can be used if desired.
What’s needed
Notebook, pencil, long
tape measure (preferably more than 10 metres long), sheets of graph paper or
plain paper. Optional: a tree
identification book and a saw.
Getting started
1. Together with your child, select a natural
wooded area in your community in which there are a fair number of trees.
2. Ask your child to begin by making a rough
estimate of the number of different types of trees in the area.
3. Suggest that your child focus on one
particular type or species of tree. A
good starting point is to examine the type of trees that have the thickest
trunks. Have your child measure the
distance around the trunk of the largest trees (the circumference). In order to have a point of comparison,
encourage your child to take the measurement at same height for each tree (that
is, choose a standard height above the ground - breast height is
convenient). Move on to the smaller
trees of this same type. Record the
measurements of lots of trees, big and small;
one hundred if possible. Don’t
be selective.
4. At this stage, when
your child has found the approximate range of tree sizes for a particular tree
species, it might be fun to have a contest to see who can find the fattest
tree. This works well if there are several
children or family members involved.
5. Chart the results
using a bar graph (also called a histogram). The horizontal axis represents circumference
and the vertical axis, the number of trees. For easier plotting of the circumference, choose intervals that are appropriate for the data
collected, (e.g. 0-50 cm, 51-100 cm, 101 - 150 cm etc). The length of the bars on the vertical axis
should reflect the number of trees you found in each category.
Questions:
1. What is the average
(or mean) tree circumference? The average is calculated by adding up all the
circumferences and dividing by the total number of trees measured.
2. What is the most
common circumference? Is it the same as the average (or mean)? If not, why not?
3. What is the smallest
and the largest recorded circumferences?
4. Make an assessment of
what stage your tree population is in. Look at the data you have
collected. Is there a more or less
continuous range of sizes from very large to very small? If a population is
actively regenerating itself, it should contain small seedlings, and all sizes
of trees from there on up. If the range of tree sizes does not extend down to
seedling size, the population might not be actively regenerating. Look for
clearings caused by windfalls, or look at the edge of the population; are there
seedlings in these locations? If so this might show that regeneration is
occurring. No seedlings, or the presence of seedlings of another species of
tree might indicate imminent replacement (ecological succession – see also
Activity 12). When the present trees reach a certain size, they will die from
disease or windfall and may be replaced by another species. Broadleaf trees often precede coniferous
(evergreen) species in this way.
Taking it further
1. Repeat for another
tree species in the same wood, perhaps the second most common. Compare numbers
and the histograms - are there differences? If so, suggest a reason.
2. Find a fallen tree,
preferably one with a cut end. If not, cut off the end of a fallen tree with a
saw. The aim is to see the growth rings, which are laid down one per year. Counting the number of rings will give a
measure of the age of the tree.
3. It is possible to use the information
provided by the fallen tree above to discover the approximate age of any of the
other trees measured. Begin by
measuring the radius of the tree, that is, the distance from the centre of the
tree to the outer edge. Use this
information to calculate the number of rings per cm of radius (e.g. 2 rings per
cm). This tells you that it took 2
years for the tree to add one cm to its radius.
The original data you
collected measured the circumference of the trees, not the radius. However, it is possible to find out the
radius of any of the trees as the relationship between the radius and the
circumference is always the same:
circumference = 2 x p x radius (p is a
mathematical constant, approximately 3.14).
Rearranging this
formula,
radius = circumference /
2 x 3.14
so, radius =
circumference /6.28.
A tree that has a
circumference of 73 cm, for example, must have a radius of 11.64 cm (73 / 6.28
= 11.64). Since we know that the trees
in this area added 1 cm to their radius every two years, a tree with a radius
of 11.64 cm would be approximately 23 years old (11.64 x 2).
You can easily make an
age distribution for the trees in your sample by converting all their
circumferences to ages!
14. Colonization of rock surfaces in water
What’s it all about?
Plants and animals are
constantly competing for space in which to live. A new generation of any
species has to find its own space in a process called colonization (“making new
colonies”). In the present exercise, the child provides a vacant space under
water, and documents the process of colonization by various aquatic plants and
animals over time.
What’s needed?
Some flat bare unpolished
rocks, the larger the better; around 30 cm is perfect. Notebook.
Getting started
This exercise requires a
body of water, either a stream/river, a lake/pond or the ocean.
1. Obtain some flat
rocks with bare surfaces, i.e., with no encrusting plant or animal life.
Rougher surfaces will probably encourage more colonization. Even bricks or
cement slabs would be fine. These will provide surfaces for the attachment of
plants and animals to start colonies. Many aquatic plants disperse by cells
(spores) that float around and settle on a new surface. Likewise, animals often
disperse by small, motile larvae that swim around and settle down in a new
location.
2. Place the rocks in
various positions under water. Exercise great caution near deep or rough water. Try:
- different
distances from the shore
- different
depths (very deep locations could be tested by tying a line around the rock and
lowering it from a boat and tying the line to a float for future retrieval).
- different
degrees of turbulence (fast running or still water; surf or quiet pools).
3. Re-examine the rock
surfaces over time. Record the changes you see. Remember that although some
colonies are easy to see (such as attached animals like snails) some colonies,
especially in the early stages, look just like crusts or paint on the surface
(some algae are like this). Make sketches of the encrusting forms that appear.
Be sure to compare the upper and lower surfaces and record differences. Place
the rocks back in the same orientation they were before. It might be useful to
scrape some material off the rocks to examine it under a lens or microscope, if
available.
Taking it further
1. Try different
locations.
2. Try different types
of surfaces, such as wood (weighed down), metal or plastic.
3.
Investigate
how the presence of animals and plants change the surfaces they reside on. Do
they make the surface rougher? Smoother? A different colour?
Acknowledgements
Many
thanks to Dr Barbara Moon (Biology, University College of the Fraser Valley)
and Dr Jolie Mayer-Smith (Curriculum Studies, University of British Columbia)
for their inspiration and help in preparing these exercises.