Take a glass of cold water with several medium ice cubes floating in the water. Get the end of a sturdy piece of string wet so it will sink rather than float on the top of the water. Drop the string onto one or more of the ice cubes and drop a little salt on top of the string and ice. Wait about 15 seconds and lift the string. The string should be frozen onto the ice cube and allow you to remove the ice from the glass.
This works because salt lowers the freezing point of the water in the ice and causes it to thaw. However, as the string sits on the ice in the cold water, the ice will cause the melted section to refreeze and imprison the string onto the ice.
Take a head of red cabbage chop it into small pieces. Add it to a pan of hot water and boil it for about 15 minutes. Strain the cabbage out and allow the liquid to cool. You have created a liquid that will react to acids and bases.
Pour about 1/3 cup of the liquid into each of two clear cups. Set the cups on piece of white paper inside a larger container with sides. Add one teaspoon of baking soda to the first cup and swish it around. Now add a teaspoon of vinegar to the second cup and swish it around. Note the color change in your liquids.
The baking soda is a base and turns the liquid one color. The vinegar is an acid and turns it a different color. Mix the two liquids together and observe the reaction when a base and an acid are mixed.
Pour enough whole milk into a container to cover the bottom. Add two drops of different colors of food coloring to your milk, placing the drops in various spots in your container. In a separate container, mix a teaspoon of dishwashing soap with 1/2 cup of water. Dip a cotton swab into the soapy water and touch it to the milk. The soapy water makes the milk and coloring swirl.
The soap breaks the surface tension of the milk, swirling it with the coloring. When new milk comes to surface, surface tension reforms until you add more soapy water.
Heat one cup of water to boiling. Add a small amount of salt, baking soda, Epsom salts or sugar. Stir until no more solids will dissolve. Strain the liquid into a jar and suspend in it a string tied to a craft stick. Cover the jar with a lid or paper. As the water evaporates, crystals will grow along the surface of the string much as they grow in a cave.