Learners create a small explosion by collecting hydrogen and oxygen gas together and squeezing them into a flame. Two test tubes are used to generate the gases: zinc and hydrochloric acid to produce hydrogen gas, hydrogen peroxide and manganese dioxide to produce oxygen gas. A stopper with a hole is inserted in both the test tubes, and learners fill a small pipette bulb with water. They let the gases from the two test tubes displace the water. The gases are squeezed into a flame to make a "pop," and the gas ratio can be varied to change the magnitude of the "pop." This reaction can be related to the hydrogen/oxygen reaction that powers the space shuttle. For safety reasons, this activity works best as a demonstration for younger audiences.