Mix the flour, coffee grounds, salt, sand, and water together. Form the mixture into round, flat balls; if desired, decorate the balls with food coloring or glitter. Press an "artifact" firmly into each ball then carefully remove it to reveal an impression. Place the balls on a cookie sheet lined with waxed paper and bake for 20 minutes at 150 degrees F. Upon heating, the balls will shrink slightly. Once the balls have cooled and hardened, the fossil is complete. Alternately, "artifacts" could be hidden inside the balls. With this method, once the balls have cooled, use a small hammer to break it open and discover the hidden treasure.
Used with permission from Discovery Place, Charlotte, North Carolina.
Put an empty glass bottle in the freezer overnight. Take the bottle out of the freezer and quickly put a penny over the mouth of the bottle. Hold both of your hands tightly around the bottle. The penny should begin to jump up and down because the heat from your hands flows through the glass and warms up the air inside the bottle. As the air gets warmer, it expands, pushing up on the penny and making it jump.
Used with permission from Sci-Port Discovery Center, Shreveport, Louisiana.
Fill cup halfway with glue. Fill the rest of the cup with water. Stir in Borax with a craft stick until glue is completely mixed. (Since Borax is a bleaching agent and the solution will burn the eyes, parents should do this part of the experiment.) Pour off any excess water and knead by hand. Then play with it: See if it can be flattened, twisted, stretched, or bounced. Place the slime in a sealed plastic bag in the refrigerator. Don't let it dry on surfaces because it will bond to them. Wash hands after finishing the experiment.
Used with permission from Chabot Space & Science Center in Oakland, California.