We put a small jar, half-full, of olive oil into the refrigerator last night. This morning, we will take out the jar and look at the oil. Tip the jar and see what happens. Nothing! It's hard, isn't it!

We'll take it's temperature to see how cold it is, and then put it on the counter by a sunny window. Keep an eye on it, so we can tell when it begins to melt.

When we see a little liquid on top of the hardened oil, we will know it has started to melt. We'll get the thermometer again, and, by tipping the jar, we can take the temperature of the melted oil. What will that tell us? It will tell us the "melting point" of hardened olive oil.

There are some other substances in the refrigerator, which we will also take out and put near the sunny window. A jar with an ice cube, little dishes of butter, margarine, lard, ice cream, and a square of chocolate. Will they all start to melt at the same time?

When there is a little liquid in each of the containers, we will take the temperature of the melted substance, and write down the melting point of each one. Which substance has the lowest melting point?

OOPS! The chocolate didn't melt! Why do you think that is?