Food
Chain
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Lyvonia G.
Hearns |
Retired and feeling Wonderful! |
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Objective(s):
Create
different types of food chains.
Compare
a balanced food chain to an unbalanced food chain.
Primary
Grades (Kgn, 1st, 2nd,
3rd.)
Materials:
Peanuts
in the shell or candy in a wrapper
(hard candy) (approx. 150) of each.
Set-up:
Large
open area – circle to start; may wish to
break the class in half & work with one half at a time.
Strategy:
When
you need energy in the morning before you come to school what do you
do? Eat
breakfast. Review that living things need food to give them energy.
Plants get
energy from sunlight. Grasshoppers get their energy from plants. Birds
get
their energy from grasshoppers. Draw the food chain on the board as you
go
along. Explain that this is a food chain. The plants and animals in a
food
chain depend on each other to live. What would happen if all the plants
died?
(Erase plants from board) Can grasshoppers get their food or energy
from the
sun? No. The grasshoppers would die. (Erase the grasshoppers) All the
animals
that eat/ depend on the grasshoppers would die too. So every part of
the chain
is important.
Today we are going to experiment with creating our own food chain. We are going to have the sun’s rays (teacher and 3 students), some plants (16), some mice (11), some snakes (7), and some hawks (3). Break students into groups (suggestions: group by clothing – i.e. pick 16 people in green to be plants, etc). Have all the plants sit on the floor next to each other in a straight line. Behind them have the mice sit next to each other (facing the plants’ back), behind them the snakes and behind them the hawks, (to form a pyramid) [ Option: if space is limited have the plants create an outer circle, the mice inside, the snakes inside them and the hawks at the core.]
Explain
that you and your 3 helpers are the sun’s rays and that you have energy
(peanuts in the shell) to pass out to the plants. Give each plant a
handful of
peanuts (at least 16). The plants should keep 2 peanuts (do not eat
yet) and
pass the rest to the mice behind them. Make sure you notice how many
peanuts
are handed to you before you pass them on. The mice should keep 2
peanuts and
pass the rest to the snakes. The snakes
should keep 2 peanuts and pass the rest to the hawks. The hawks should
end up
with a lot of peanuts. (Do not eat the peanuts yet).
Discuss
how the chain worked (everyone got food – well distributed, the sun was
the
original source of energy, all the participants depend on each other).
Who got
the most peanuts? Why do the hawks need the most energy? (They are
bigger, they
need more energy to move and fly). Make
comparisons between a big athlete like Shaq and a kindergarten student.
Who
would need more food for energy?
Collect
all the peanuts and explain that now we are going to see what happens
if the
food chain is not balanced. This time there are no hawks because humans
that
were hunting killed them all. What that means is that since there were
no hawks
to eat the snakes we have even more snakes than before. Have all the
hawks now
become snakes and join that group. Start the chain as before, (Every
student
keeps 2 peanuts). What happened when we got to the snakes? Did each
snake
receive more food or less food than before from the mice? (Less) When
there are
too many snakes there is not enough food for them all and some will die
of
starvation. We need the hawks to balance the chain.
Collect
the peanuts and put the hawks back in their spot. This time we had a
bad
drought and only half of the plants survived. Only give out peanuts to
half of
the plants (or half as many peanuts to all the plants)
Keep the same numbers of students in the
other groups. Continue the chain as before keeping 2 peanuts as before.
What
was different this time? Did everyone receive as many peanuts as they
did the
first time we did this? No. Some of the animals will die off because
there
isn’t enough food for everyone, (hawks may not receive any peanuts).
Performance
Assessment:
Students
will fill in an observation chart or (make a chart) by choosing a food
chain
for each animal or plant listed in the lesson.
(i.e. sun – corn-cow-humans).
Conclusions:
We can see from our experiment today that food chains need to be balanced. Now you can eat your peanuts.
References:
Hands
on Nature,
Vermont Institute of
Natural Science, 1986
Critters, AIMS Education Foundation, 1989
Science
on the Go! The
Chicago Academy of
Sciences