Lyvonia G. Hearns
Retired and feeling Wonderful!
Create different types of food chains.
Compare a balanced food chain to an unbalanced food chain.
Primary Grades (Kgn, 1st, 2nd, 3rd.)
Peanuts in the shell or candy in a wrapper (hard candy) (approx. 150) of each.
Large open area – circle to start; may wish to break the class in half & work with one half at a time.
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).
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).
We can see from our experiment today that food chains need to be balanced. Now you can eat your peanuts.
Hands on Nature, Vermont Institute of Natural Science, 1986
Critters, AIMS Education Foundation, 1989
Science on the Go! The Chicago Academy of Sciences