How the Earth moves has always fascinated me. The formation of mountains, the movement of the continents – all that just seems so impossible, but it happens. Earthquakes, tsunamis, volcanoes – these are all results of the movement of the Earth’s plates. My children seem equally fascinated by these forces as well. It is always easier to teach children about their interests – so I made some earthquake gelatin to show them how the Plate Tectonics works, and made our Science in Action: E is for earthquake a physical science exploration for preschoolers.
Objective: to introduce children to the different movements involved in Plate Tectonics.
Preparation: This activity requires a two layer gelatin. Set the first gelatin as directed, pour into a 9 x 13 pan, and allow it to cool for at least two hours. (The more time the first gelatin has to set, the better the layers turn out.) Next, mix another gelatin and pour it on top of the first gelatin. Let both solidify completely.
I made up the gelatin the morning before we were going to do this activity, that way the gelatin was very solid – which is important. When it’s time for the activity, cut large squares of gelatin, about 4 inches by 4 inches, and place them on plates – one for each child participating.
First, make sure that the children wash their hands thoroughly before beginning.
Begin by having the children examine their gelatin. Explain that the top gelatin represents the Earth’s crust. Talk to the children about how the Earth’s crust is floating on the mantle – which is mostly liquid rock called magma, and is represented by the second layer of gelatin.
Have the children jiggle the gelatin. Talk about how earthquakes send waves of energy through the mantle and the crust. These waves are reproduced in the gelatin when it is jiggled. Also, jiggling the gelatin shows how the waves affect the ground, buildings, etc.
Now, have the children grab both sides of their gelatin and pull in opposite directions, one hand toward the body and one hand away from the body. This simulates when two plates push past each other, as in a strike-slip fault. The San Andreas fault in California is an example of a strike-slip fault. Have the children look at the layers of the gelatin and see if they are mixed up very much. A Strike-slip fault doesn’t normally make the mantle and crust mingel. However, deep chasms and holes can open up during a strike-slip fault earthquake.
Next, have the children push one piece of gelatin over the top of the other piece. This represents a subduction fault. This type of fault forms many of the world’s volcanoes. The Hawaiian Islands have been formed because of the subduction fault along the bottom of the Pacific Ocean. Again, have the children look at the layers in their gelatin. Ask them if they see any change in how the crust and mantle are laid out. Explain that with a subduction fault the crust of the plate being forced underneath will melt and become new mantle for the other plate. Also, explain that lava is what the mantle becomes once it comes out of the Earth.
Finally, have the children push both pieces of gelatin together. This creates a thrust fault. Have the children do it slowly so that a mountain of gelatin forms when the two plates meet. Mount Everest is an example of a thrust fault. Have the children take another look at their gelatins. Ask them how their layers look. The upper layer of the gelatin should be crumbly and mashed into the upper layer of the other part of the gelatin. Explain that in thrust faults, the two plates usually end up mashing into each other and mixing their crust layers together.
After all this pushing, pulling, and shearing, the gelatin is going to be in a lot of tiny pieces. Have spoons ready and either let the children eat the mashed up gelatin, or give everyone a new piece of gelatin to eat.
My children really enjoyed playing with their food this way. They loved making the earthquakes. Seeing the way the gelatin reacted to the various forces made an abstract (unless you’ve experienced an earthquake) concept more understandable. My kids were amazed to learn that the solid ground they are standing on can act like the gelatin acted when it was being poked.