Tropical Rain Forest Project for Kids

Earth Science Unit Study

Week 12: We made two different types of hygrometers to measure humidity.

Tropical rain forests are the most inhabited places on the planet. Plants thrive in the hot, humid and wet environment providing an abundance of food for animals.


The video Living Planet - Jungle provides glimpses of many unique plants and animals of the rain forest including native tribe who have learned to live in the unusual environment.

Rain Forest Books
Welcome to the Green House by Jane Yolen is a picture book of the rain forest good for young children. After watching the video the kids were excited to recognize many plants and animals in the story.

Generally my children shun non-fiction books in favor of stories, but they did enjoy Rainforest Babies. Each page detailed a different rain forest animal with interesting information. They were fascinated by the frogs so poisonous they could kill an entire village. Did you know chameleons weren't born knowing how to change color? They learn it like we learn to walk, and they communicate through color.

In the Rain Forest: A Book about Rain Forest Ecology (Magic School Bus) is a book my kids loved even before it was opened. As the kids journey through the rain forest they learn where chocolate comes from and see many plants and animals.

Rain Forest Maps
Most rain forests are located near the equator, so we printed world maps and labeled the  rainforests.

Hygrometers
Since rain is essential to life in the rain forest, we made two different hygrometers to measure humidity. Both projects came from the book Janice VanCleave's A+ Projects in Earth Science: Winning Experiments for Science Fairs and Extra Credit.

The first type of hygrometer was constructed using two short pencils, two glass jars, two empty spools of thread, newspaper, aluminum foil, and tape.

Two of the first type of hygrometers were created. One was to be placed in a dry environment and the other in a humid environment. That way it was possible to see how a hygrometer would look in different situations.

A strip of newspaper was cut and taped to a slightly larger strip of aluminum foil, and then coiled around one of the pencils. The pencil was stuck into the spool to enable it to stand up, and placed in one jar.

The set-up was repeated for the second jar.

While one jar was dried out with a hair dryer, a bit of warm water was placed in the other.

After the hygrometers had time to adjust to their environment, the one in the humid environment was coiled looser than the one in the dry environment. As the newspaper absorbed water, the paper pushed against the foil causing it to unwind.


Once the hygrometers came to equilibrium in their jars, the lids were removed so they could be viewed moving once again. By letting them sit with their lids off, changes from day to day were slightly visible.

Hygrometer #2
The second hygrometer involved tying a strand of hair to a thumb tack and an indicator. As the humidity in the air changed, the length of the strand of hair changed too.

The hair was attached to one thumb tack, and the hole punched in the triangular indicator. Next the hair was stretched tight and the indicator was tacked down to the cardboard so that it could rotate as it's length changed due to the humidity. A line was marked to show the initial position of the indicator. The following day when the humidity dropped from 85% to 60%, the indicator pointed to a line slightly higher than the original line.

In doing this project, my son was shocked to learn that his hair changes length in accordance with the weather.





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