Beacon Lesson Plan Library

Understanding Our Planet's Food Web

Richard Angelini Sr.

Description

A team structured problem-solving activity that challenges the student's problem-solving ability. Students understand man's tenuous position in the environment and learn through a hierarchy of decision stages to conserve species diversity.

Objectives

The student understands that humans are a part of an ecosystem and their activities may deliberately or inadvertently alter the equilibrium in the ecosystem.

Materials

Per Team:
-1/2 cardboard box, enough to cut out 42 pieces of cardboard, each 1 by 3 inches.
-Scissors
-Clear tape
-Pen or pencil
-Ruler

Preparations

1. Obtain about 2 square feet of cardboard for each team. Most food stores have some around for their customers.
2. Make sure you have one pair of scissors, a ruler, and some tape for each group.
3. Take a look at the grading rubrics in the assessment section.

Procedures

--Introduction: (5 minutes)
Ask the class the following question “Is it really important to you today, right here in the classroom, right now personally to you; if some snail, (hypothetically), in Africa becomes extinct and why?” Students will find it hard to say why that extinction will affect them in the classroom today. Many will repeat a long list of reasons memorized, but few will be able to tell you why, personally. Write down on the board a few answers.

--Step 1: (7 minutes)
Instruct each team to make 14 cardboard blocks. Each block must measure 1 inch by 3 inches using 3 pieces taped together . One block must be labeled: “humans.” If they wish the students may label all the blocks different plant and animal species.

--Step: 2 (7 minutes)
Instruct the teams to construct a model of a food web. Tell them that a food web is a model of all species humans need in order to have enough to eat. (Observe to see if the students realize that some species we eat depend upon other species we do not eat). At this stage most students will build a food pyramid with humans at the top and grains at the bottom. Now, at each team table, remove one block from the bottom of the model. Choose one that will make the model fall apart, causing the human block to fall. Tell the students: “Block falling represents the extinction of that species.” (Some students will gasp.)

--Step: 3 (5 minutes)
Next instruct the teams: “Construct a model that offers better security of the food supply to the human block.” They will have some heated discussion about what to do. This puts the students inside the problem. Mentally they surround themselves with the various options. (We want them to do this mental process). Teams will begin to place humans in the center of the model, and not on top.Now, at each team table, remove one and then two or more blocks until the human block is in great danger of falling, (extinction). Ask the following question: “What would be better, make you feel safer; the model as it is now or the model the way it was before I removed some blocks which represent extinction?- Now ask the students again about that African snail discussed in the introduction!

--Step: 4 (10 minutes)
Ask the following question: “Is it better for humans to have a few species to eat or many?” Next instruct the teams to build the best model for human survival. Tell them to use what they have learned. Tell them to prepare to explain to the class why their team’s model is the best. Suggest they take notes. The most efficient models will have humans in the center, and on the bottom in contact with as many species and possible. This design almost totally requires a one layer high, flat model. The idea of humans on top now seems a dangerous folly.

--Step: 5 (11 minutes)
Class discussion and team explanation of the models. At this time introduce the concept of increased scientific discovery to help insure food supplies as human population increases. Say: “Can we humans expect and should we plan on science to come to our aid? Can we afford to simply assume that each year will bring increased food supply?”

Some collegues have expressed the concern that perhaps 45 minutes is not enough time to complete the experiment. Let me clearly point out that this is an experiment performed on the students in your class, by the students in your class. They must feel the urgency of decision making to experience the urgency of saving species from extinction. Consider the Amazon rain forest. How many species are lost there forever in just one year? I suggest you perforn the experiment with your collegues prior to the classroom. Caution: you cannot experience the construction of knowledge by simply reading the directions. This experiment gives the participants REAL experience in species extinction through modeling. It emotionally expresses the predicament humans are placed in every time another species bacomes extinct. (Emotions are a potent way of learning). Remember, a food web is global; we have only one. (The term food chain is archaic). What happens to a snail half way around the world will impact humans in some way. That is what this experiment allows the students to experience.

Possible homework or further class discussion:
Construct further improvements of models.
Construct a political plan for preserving species.

Assessments

Checklist for Assessment
This checklist is to be used to assess student performance after the experiments are completed. It is designed to assess knowledge construction. Students will define the problems together. In teams, students will pose solutions to the problems observed.

Solution to the problem of humans on top of a pyramid. Place humans inside the food web where they can get to many species for food.

Solution to the problem of food web collapse and loss of the human block. Place the human block in a position at the most stable location which is at the bottom and in the center.

10 points: Solution to the problem of risk of loss of part of human food resources. Place the human block where it can touch all of the other blocks. This will insure the most possible food for humans.

5 points: This one is for those A+ students in your class. Some student will observe that it is still possible for humans to lose some of their food supply relative to increased population. The solution is a combination of conservation, management, and new scientific discoveries. Have the students construct several possible solutions.

Keep team scores of the board during the experiment phase of the lesson. Reward all input as deemed appropriate.

Extensions

ESOL friendly uses a minimal amount of verbal communication. It employes modeling and team effort to construct new knowledge in a non-verbal format.

Web Links

Web supplement for Understanding Our Planet's Food Web
Webgame

Web supplement for Understanding Our Planet's Food Web
Foodchain

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