This is an oldie but a goodie, and definitely worth a look. Building a baking soda volcano in your kitchen is a fun science project that has the added "wow" factor of an explosion (without really having anything explode). It's great for a rainy day, a summer day, or any day you're trying to show your kids just how cool science can be. Here's how it's done:

What you need:

6 cups flour

2 cups salt

4 tbsp. veggie oil

2 cups warm water

Red food coloring

5 drops dishwashing detergent

2 tbsp. baking soda

1 empty soda bottle (2-liter or 20-ounce, depending upon how big you want your volcano)

To make the volcano, mix flour, salt, oil and water until it is smooth and firm. Place the plastic bottle in a baking pan and mold the dough around it, shaping it into a volcano. Be sure to keep the bottle opening free of dough. Fill the bottle two-thirds full with warm water and a few drops of food coloring. Add detergent and baking soda to the liquid in the bottle. Slowly pour vinegar into the bottle and get ready for an eruption of lava (and kids' smiling faces!).

Fun fact: Baking soda and vinegar mixed together produces carbon dioxide gas, which bubbles up (with the help of detergent) and forces the "lava" to erupt.