Providing students with an ice cube, a glass bowl and a candle will give them the opportunity to see the three common states of matter: liquid, gas and solid. The water changes into the three states as the solid ice cube melts and becomes liquid. By using the candle, the third state, gas, is formed. Students see the gas return to a liquid in the form of condensation with the glass bowl is held over the steam.
To visually demonstrate the fact that physical change happens when a substance does not change anything but the appearance of the item, provide students with items such as sheets of paper, pieces of cloth or miniature terra cotta pots. By ripping or crushing the paper and by cutting the material, students make the observation that the pieces have the same properties as the original shape. The same fact can be demonstrated by placing the terra cotta pot inside a paper sack and striking it with a hammer or just hitting it on the floor. Once the experiment is complete, the students will be able to participate in a discussion about physical changes.
Some experiments appear to be chemical changes but are actually physical changes. When a cup of water is saturated with salt, all visual evidence of the salt disappears. When a string is lowered into the water and left there while the water evaporates, the salt remains behind, bearing the same physical and chemical traits as it had before the experiment. Making rock candy is another way to demonstrate the same principles with an added element that the students enjoy; they can eat the candy when the experiment is completed.
Another simple physical change can be observed with a bar of soap and a plastic knife. Students can carve any shape they wish from the soap while observing that the soap maintains the same physical and chemical properties. By washing their hands with the soap shavings, students see that the soap still works just as it did in bar form.