Mudslides are dangerous events that typically occur after intense rainfall and in sloped areas. When the soil on the hillside becomes wet, the resulting mud flows down the slope, sometimes at high speeds and with enough thickness to carry boulders, trees and even homes. While it’s unsafe to experience a mudslide firsthand, kids can get an idea of their destruction and the way they work through a hands-on experiment.
Ask your kids to think about different kinds of dirt, such as sand, clay, pebbles or a mixture -- which types of soil do they think would be more prone to a mudslide? In your experiment, you will test various types of soil, and soil with plants and trees. Do your kids think the soil alone or soil with plants will prevent mudslide activity? Help your kids come to the conclusion that the soil with plants and trees will have less mudslide activity than just soil alone.
Gather your materials for the experiment -- you will need a stream table or an object that acts like a stream table, such as an aluminum baking container. You will also need soil, soil with grass (roots included) on top, toothpicks, paper cutouts in the shape of trees, nontoxic school glue, pebbles, sand and water. You can use books to vary the angle of the slope of your stream table.
To prepare your experiment, fill your stream table halfway to the top with soil. You might want different stream tables for each type of soil, or you can fill one side with a particular type of soil and the other side with another type. For your hypothesis, you should have one section with just soil and another section with soil, soil with grass and toothpicks to represent tree roots. You can glue the paper cutouts of trees on the toothpicks to make them seem more realistic, so you have mini trees sticking out of your soil. You can also have a stream table with sand and soil with pebbles mixed in to see whether these types make a difference.
Place books underneath one edge of the stream table, so the table looks like a hillside. Pour a measured amount of water, in case you repeat your experiment with a different variable, at the highest edge of the stream table. Continue pouring the measured amounts of water until the soil starts to move toward the bottom of the table. Which kind of soil was carried faster or in larger amounts toward the bottom of the “hill?" Did the grass and trees prevent soil from flowing in a mudslide? Was your hypothesis proven?
In addition to experimenting with the various types of soil, you can try different angles of slope to see whether that variable makes a difference. Simply use the same experiment but repeat it with more or fewer books holding up one end of the stream table. Help your child make miniature houses out of construction paper to see whether they can withstand the mudslide.
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