How to Make a Paper-Mache Volcano

Draw a line around the bottom perimeter of the cardboard box, making a shallow tray about 3 inches deep. Above this edge, draw a triangular volcano shape on one long side of the cardboard box, making sure it's slightly taller than the bottle -- this is the back of your volcano. Cut away the cardboard above your lines, leaving only the shallow tray with a volcano shape at the back.

Trace the bottom of the bottle a few inches in from the back side, at the tallest part of the volcano, and cut out the circle, making sure the bottle can slip easily through the hole. Cover the bottle with a plastic bag to protect it from the messy, paper mache process. Place the bottle in the hole.

Cut strips of cardboard from the discarded parts of the box and tape them from the base of the box tray to over the top of the bottle, leaving a small open circle around the bottle's mouth. Use enough strips to create a three-dimensional volcano. Stuff the open spaces underneath and between the cardboard strips with crumpled newspaper to give the volcano frame more strength.

Rip the newspaper into strips or the paper towels into squares. Mix equal parts water and flour in a mixing bowl, and add a tablespoon of salt to act as a preservative. Dip pieces of paper into this gluey mixture, soaking them thoroughly. As you life each piece of paper out of the bowl, wipe off excess paste with your fingers. Apply the wet paper in layers to the frame of the volcano, allowing for some wrinkles and ridges to give the look of rock.

When the volcano is thoroughly dry, paint it with acrylic or tempera paints, using brown as the base color -- or green to make it appear more lush. Paint fiery orange and red lava at the top -- start with orange all around the volcano opening, extending downward in drips, and add red streaks for depth.

Remove the bottle through the hole in the bottom of the volcano and take off the plastic bag. Fill the bottle almost to the top with water. Add a few drops of dish detergent followed by the baking soda. Pour a little vinegar into the top of the bottle; then stand back and watch your volcano erupt!

The project demonstrates an acid base reaction, where the acidic vinegar reacts chemically with the baking soda base. Mixed together, they release carbon dioxide that bubbles up. This is enough for the experiment, but the detergent makes the "lava" more foamy for better visual effect.