Show pictures or videos of real volcanoes. Discuss the purpose of the experiment, such as explaining how a volcano erupts. The lava for the experiment works because of the chemical reaction between vinegar's acid and the base baking soda.
Prepare for the mess. Conduct the experiment outside, if weather permits. Alternatively, cover a table with plastic, such as a drop cloth or cut-open garbage bag and cover the plastic with newspaper.
Place cardboard inside a cookie tray for each volcano experiment. This provides a support for the model and the cookie baking sheet catches the lava flow from the eruption.
Make a modeling clay volcano. This version is more durable than paper mache or homemade clay volcanoes and it's ready to erupt as soon as it's built, without the drying stages and extra time to paint the model that can be frustrating for kids.
Show the kids how to glue the base of a 16-oz soda bottle in the center of the cardboard base. Direct them to form the shape of the volcano by smoothing balls of modeling clay around the base of the bottle and tapering the shape of the volcano as they add more clay up to the top of the bottle.
Guide the kids through creating the lava mixture. A 16-oz. soda bottle in the middle of the volcano model works well for a lava tube. Direct the kids to pour 1 cup of vinegar, 1 tablespoon of dish soap, eight drops of red food coloring and three drops of yellow food coloring into the bottle, and then to add 2 tbsp. of baking soda in a twist of tissue to set off the eruption.
Let the kids repeat the volcano experiment multiple times for the fun of making the volcano erupt.