Students often confuse observable properties of a substance with properties of its molecules. For example, many students believe that molecules of ice are hard and cold. They also think that water and ice are composed of different kinds of molecules. Some students think that molecules have a bonding agent similar to the toothpicks that hold the atoms together in "Making Water Molecules".

The misconceptions that students have regarding the distinction between observable properties of matter and the nature of molecules should be carefully treated. As the scientific conclusions regarding matter are not necessarily intuitive, it is easy to understand how a student might formulate erroneous ideas. Therefore, teachers need to be aware of what children think in order to effectively correct misconceptions.

One way to lead the students into a dialogue of models is by holding up a small toy car. Why is it like a real car? Why is it unlike a real car? Work with students to develop a definition of a model.

---

Making Water Molecules