Food and the Environment
by Michael Eversoll
In the fifth grade, we teach an eight-week environmental unit. Below are a couple of the activities we include.
Acid rain simulation
We talk about what it takes to grow plants effectively. We make a small greenhouse in our room and keep it lit by fluorescent bulbs twenty-four hours a day. Then we estimate how long it will take for bean plants to grow in this environment. Many students are really amazed how fast they grow. After they are full grown, we talk about what things in the environment can hurt plants. Many students will say acid rain, but really don't understand what it is or were it comes from. We talk about the pollution that comes from factory smoke stacks, automobiles, airplanes, etc., (nitric and sulfuric oxides). Then, we discuss where it goes. After understanding that pollution does not go away when it goes up into the atmosphere, we talk about the precipitation combining with the pollutants, which then waters our plants. The goal is for students to understand that different levels of acidity affect plant growth and development. To stimulate the concept, we use bean plants and vinegar. We make a concentrate of four different levels and water them two different ways. One group waters their plant on the leaves. The other group waters theirs on the roots.
Level 1 (pH3) no tap water/1 liter vinegar
Level 2 (pH4) 1 liter tap water/125 ml vinegar
Level 3 (pH5) 1 liter tap water/10 ml vinegar
Level 4 (pH6) 1 liter tap water/no vinegar
normal rain pH range 5.05.6
So we actually have eight different plants being tested.
Level 1 roots, Level 1 leaves
Level 2 roots, Level 2 leaves
Level 3 roots, level 3 leaves
Level 4 roots, Level 4 leaves
After the experiment, which takes anywhere from 3-7 days, we talk about the following connections:
How do you think acid rain may affect you, the dog next door and a bald eagle?
We want students to understand the problem we have with landfills being overcrowded. We talk about a couple of comparisons that they might be able to relate to:
Two ways that we can take care of the landfill problems are to recycle and compost.
Composting, which is based on the biological process of decomposition, is a fascinating educational activity. When people make composting piles and bins of organic material, they encourage the natural process of rotting and the resulting compost is a dark, earthy smelling, crumbly material that is the best natural fertilizer in the world. Composting returns organic wastes to the earth, recycling them for use by other forms of life.
A compost column is made in a plastic bottle. We have students bring in whatever they would like to fill the columns. We make scientific observations recording our findings every few days over the course of about nine weeks. Students begin to notice results after approximately two weeks. Then we predict what will happen in the next few days. After this composting gets going, students ask lots of questions and then you have the opportunity to teach lots of science. The science I'm referring to are the "teachable moments" which come from questions the students ask.
What turns dead plants and animals into compost? Microscopic bacteria and fungi, which feed on dead tissue, are the chief agents. These organisms are everywherein the air, on the leaves of plants and in the soil. Different kinds of organisms specialize in breaking down particular types of tissue. Certain varieties thrive early in the rotting process while others come along at the end to finish the job. Their activity releases a variety of nutrients, as well as water, gases and heat. "How many different kinds and colors of fungi and bacteria can you seeand when do they appearin your column?"
We then have the students take the remains of their compost columns and use these remains as fertilizer in the garden. Making a compost column lets one see this process and witness nature's world of recycling. After this experience, the students get very interested in starting their own compost bins at home. The only drawback in this whole activity is the number of parents who come in to school or phone to ask why their child in insisting they build or buy a compost bin. The questioning from the parents is always the reward of the environmental unit.
Information on Bottle Biology can be found at: http://www.bottlebiology.org/investigations/index.html
©1991 Teachers' Laboratory (Synergy Learning International, Inc.). All rights reserved.
- Michael teaches 5th grade students in McFarland, Wisconsin. He is also currently working on a national program called 2061, funded by the American Association for the Advancement of Science. They are working on curriculum models that will change the way we teach math science, and technology. (1991)