We have used the Engineering Design Process to test materials that would stop soil from eroding. Some of the materials we used were sand, mulch and gravel.
First we set up our trays with the same materials. We used one cup of sand and four cups of soil.
Next we tested one item on each tray.
Student number 17 says: We put three cups of sand on the top of the soil, then we poured water on top. It made a river in the middle and then the sand fell in chunks to the bottom. Sand did not work by itself.
Student 18 says: We had rocks to put on top of the soil. We used three cups and patted them down. Then we put water on the top. More than a cup of run off was on the bottom. Rocks did not work by themselves.
Student number 27 says: We had sand on the bottom, soil in the middle and then three cups of mulch on the top. We didn't get any run off at first but the water came down slowly. There was no run off with the soil, just water. Mulch was the best material.
The students then took their information and designed the trays they thought would reduce the most run off. They will be testing their designs TOMORROW! We cannot wait.
