Have you ever played with a toy car or a doll
house? If so, you played with a model. A model
is a copy of an object. It is either bigger or
smaller than the real object. A doll house is a
small model of a real house. Not all models are
toys. Scientists use models, too. Models help
scientists understand things that are too big or
too small to study easily.
One big object that scientists study is planet
Earth. They study what the inside of Earth is
like. However, it is impossible to see all the way
inside Earth. Scientists use models to show the
structure of the Earth.
Scientists have learned that Earth is made up of
layers. The outer layer is called the crust.
The land you stand on is part of the crust. So is
the bottom of the ocean. The crust is thin and
made of hard rocks. It sits on a layer called the
mantle. The mantle is hotter than the crust.
Heat makes rocks in the mantle soft.
The center of the Earth is called the core.
The core is the hottest part of our planet.
You can use a model to help you understand
the structure of the Earth. A hard-boiled egg
makes a good model of Earth's structure.
The shell of the egg is like Earth's crust.
The white part is like the mantle. The yolk is
like the core.
A peach can also be a model of Earth's
structure. What part of Earth is a peach's skin
like? What part of Earth is the flesh of the peach
like? What part of Earth is the pit of a peach
like?
Discovery Education Science
© 2007 Discovery Communications, LLC