Pour water into bag of sand, and tape the bag closed.

Knead sand together in bag for 5 minutes, then open bag and mold it to the volcano form. Let sand mixture harden for 30 minutes.

Mix vinegar and red food dye in squeeze bottle, and put 2 tablespoons of baking soda in the volcano reservoir. Inject the vinegar into the plastic tube after you have attached it to the volcano form.

As the vinegar comes out of the top of the form, the volcano will fizz and erupt.