A thick layer of fat (lard) acts as insulation to keep the bodies of animals such as seals, whales and dolphins warm. Take three identical cups and fill one with water, one with shortening and leave one empty. Set them out for several hours until they are room temperature. Place a thermometer inside of each cup. Set the cups in a refrigerator, and then read the temperature in each cup every 10 minutes. Determine the value of the fat as an insulator.
Temperature can affect the expansion and contraction of various materials. Measure this by setting an empty soup can in a bowl. Slowly fill the can with water until the water spills over the top of the can and into the bowl. Place the can in a freezer overnight. The next day, observe that the water has turned to ice, has expanded so that it no longer fits in the can and has risen above the top of the can. Think about materials that do the opposite, i.e., contract when cold. For example, examine the deliberate gaps in the rails of a train track.
There are chemical reactions and physical reactions. A physical reaction can usually be reversed, but a chemical reaction usually cannot be undone. Conduct an experiment to show the difference between these two types of reactions. Because heat can cause both chemical and physical reactions, place a slice of bread in a toaster and make toast. The chemical change cannot be reversed to restore the bread back to its condition before it was heated.
Heat can also change water into steam, but this is a physical reaction that can be reversed to get water back again. Prove this by changing water into steam and then back into water. Boil a pot of water. Using an oven mitt, hold a metal cookie baking tray over the top of the pot. Place a plastic bag filled with ice cubes on top of the try to cool it. As the hot steam hits the cool metal tray it will condense and turn the steam to water. You will see droplets of water forming on the tray.
Sunlight, oxygen in the air, acid rain and other weather factors can cause materials to decompose. Locate an outside area where your experiment will not be disturbed, and set out a variety of objects to be subjected to the elements for one month. Include steel wool, a newspaper, a photograph, a rubber band (check it periodically for elasticity), an iron nail, a stainless steel nail, a piece of cloth from an old shirt, cardboard, paper clips, pencils and a plastic soda bottle. Make daily observations of the materials and note any changes. Take a photograph of the items on the first day to use as a reference for identifying changes later.