To teach students about solids, liquids and their densities, try this experiment. Put an egg in a large glass of fresh water. Slowly add salt to the water and the egg will begin to rise to the top. Salt dissolved in water increases the density of water and denser liquids are better at keeping objects afloat. Explain that this is why many things that sink in fresh water will float in salt water.
Teach children about volcanoes by making a volcano model. Fill a plastic two liter soda bottle about three quarters full of a mixture of warm water and red food coloring. Add six drops of liquid dish detergent and two tablespoons baking soda to the bottle. Slowly pour vinegar into the bottle. The vinegar will react with the water mixture, causing red foam to erupt from your volcano. The chemical reaction produces carbon dioxide, which is one of the gases that cause volcanoes to erupt. It is best to do this project outdoors.
Here is a way to test people's sense of smell. Poke holes in the top of some plastic containers and fill each container with fragrant items such as orange juice, coffee beans, pine needles, onions and vinegar. Ask for volunteers and tell them to smell each container and guess its contents. Be aware of allergies before performing this activity.
Blow up a balloon and vigorously rub it on a wool sweater. Place the balloon near a piece of paper to demonstrate static electricity. The rubbing motion will charge the balloon with static electricity and give the balloon magnetic properties that will enable it to lift lightweight objects such as paper. This project also works on hair and other light objects. Be aware of latex allergies when performing this experiment.