Cooool egg experiments using a raw egg and white vinegar e.g. Make a shell disappear, make it explode etc. The Science: When you submerge an egg in vinegar, the shell dissolves. Vinegar contains acetic acid, which breaks apart the solid calcium carbonate crystals that make up the eggshell into their calcium and carbonate parts. The calcium ions float free (calcium ions are atoms that are missing electrons), while the carbonate goes to make carbon dioxide—the bubbles that you see.
Here's an idea: Gather some of your child's favorite toys, put them in water and freeze in the freeze. When it's frozen to its core, give to your child and watch them dig for joy as they rediscover their favorite treasures!