The model is here. It’s a brilliant home ed blog in many ways, and we’re probably going to copy that exercise.
“ACTUALLY. There are two cores, the inner core and the outer core. The inner core is basically metal. It’s made of Copper, Lead, Silver and Gold. The outer core is actually a mixture of mantle and melted copper. Oh it’s quite hot but I don’t think scientists know for sure but they think it’s solid. The mantle is next. In mantle there’s tiny little bits of rare melted metal. It’s basically lava. Lava is mantle that’s come out to the surface. The crust is on top of the mantle. It is the bit we walk on. Did you know that if you dig deep enough, you hit stone still in the crust? Underneath all the soft dirt there’s stone. (What about under water?) In the oceans the crust is thinner than on land. If the oceans weren’t wet there’d be no sand in the oceans, only rock.”