Divide the class into groups of four or five children for the volcano activity. Plan for each group to sit at a table or in a circle on the floor. Provide each table group a small tray on which to place their volcano.
Gather all supplies and place them in an easily reached area. Prepare mounds of child-safe clay ahead of time. Make a mound about 6 inches high for each table group.
Gather one drinking water bottle for each table. Cut the top off the bottle so that about 4 inches remain. Make a hole in the middle of each clay mound and insert a cut drinking bottle in each one.
Place clay volcanoes on trays in front of each group. Have children watch as you place 2 tbsp. of baking soda in the center of half a sheet of paper towel. Fold the paper towel around the baking soda as if it were an envelope.
Explain the concept of volcanoes to kindergartners briefly. Show a cutaway diagram of a volcano, showing the magma chamber and the way that pressure forces the magma to rise and lava to flow out the top. Explain that the clay and water bottle represent these parts of the volcano.
Have pupils watch as you fill each group's water bottle with a 1/4 cup water and 1/2 cup vinegar. Add a squirt of dishwashing liquid to each bottle. Place 3 drops of red food coloring in each bottle and stir slightly.
Explain that it is time to make the volcanoes erupt. Instruct pupils to sit back and observe carefully but not touch the erupting lava.
Give one pupil in each group a paper towel-wrapped baking soda packet. The packet acts as a time release, building the pupils' anticipation. Have the pupil drop in the baking soda packet as all pupils watch and wait for the paper towel to get wet and release the baking soda, causing the eruption.
After the initial reaction, pupils can take turns stirring to induce more lava to flow. Pupils may also add a bit more water and another baking soda packet to create more lava.