What Models Can and Cannot Show

By the end of this lesson, you will be able to name the advantages and limitations of a scientific model by looking at its size, scale, properties, and materials.

A model is anything scientists use to represent a real object, system, or process that is too big, too small, too fast, too slow, or too dangerous to study directly. Think about the model of the solar system hanging in a classroom, with painted foam balls on wires. That model has real advantages, because you can hold it, spin it, and see at a glance that the planets orbit the Sun in the same direction. It helps you understand something you could never see with your own eyes from Earth.

That same model also has limitations, meaning things it gets wrong or leaves out. The foam balls are not to scale, which means the sizes and distances in the model do not match the real sizes and distances by the same amount. If Earth were the size of a marble, the Sun would be taller than a classroom and sit almost a mile away. The model is also made of the wrong materials, since planets are not painted foam, and the wires holding the planets do not exist in space.

Texas students see this idea outside of school too. A map of Texas on your phone is a model. It is small enough to carry and shows you which highway leads from Houston to Dallas, but it cannot tell you how hot the pavement is or how steep a hill feels under your feet.

Good scientists do not throw out a model just because it is imperfect. Instead, they ask what question they are trying to answer and then choose the model that fits that question best, while remembering what the model cannot show.

Try it: if you built a model of an animal cell using gelatin and candy, what is one advantage and one limitation of those materials?