Use flat graham crackers to mimic the force of magma pushing upward from below the crust.
This activity will require the use of an oven and should be done with the supervision of an adult.
Break or crumble several sections of crackers and press them into a thin layer covering the bottom of a cake pan. Mix a small amount of butter or margarine with the crumbles to help hold the material together. (This will serve as the boundary between the core and the mantle.) Next, break several other crackers into large irregular pieces and set them aside for now. Carefully spread a layer of marshmallow crème over the crumbled/pressed crackers. (This will serve as the magma in the mantle layer of Earth.) Gently place the broken pieces of crackers that you had set aside over top of the marshmallow crème. (Some pieces may overlap while others may have gaps between them.) Add extra crackers or other heavier objects like squares of chocolate or butterscotch pieces to provide the mass to represent heavier crustal plates. (The plates that are heavier than others will represent the continents.) Carefully heat the model in the oven on low (225o F/ 107o C) for several minutes (7-10 min). Observe the movement of the marshmallow crème (magma) upward and in between the edges of the crackers (crustal plates). Observe the shape of ridges formed as the magma moves upward between the plates.