My Science School

Believe it or not, frogs and insects help people learn about how healthy the earth is. Scientists called naturalists keep track of how many animals there are in the world. In some places, where once they saw thousands of some kinds of animals, now there are hundreds - or only dozens. A change in the number of animals tells scientists that there may also be a change in the environment, the earth, and its resources.

For example, students volunteer to help collect insects from rivers and streams. Then scientists study the insects and record their findings. Too many or too few of one kind of insect could show a change in the environment, possibly an increase or decrease in pollution.

When winter forests in North America turn cold, monarch butterflies fly to warm forests in Mexico. At one time, people in Mexico noticed fewer monarch butterflies in their forests. They weren’t visiting because people had cut down the trees and sold them to businesses. The monarchs had lost their winter homes. However, the people in Mexico saved their forests, and the monarchs, by planting new trees.