Microgravity-the absence or reduction of some of the effects of gravity-is an important attribute of free-fall. In microgravity (often incorrectly called zero-g), water no longer flows "downhill" and neither do smoke or steam bubbles rise. This changes a number of chemical and physical activities. Experiments in combustion, fluid behavior, materials formation, cell science, and even fundamental physics formed an important part of the research conducted aboard the Space Shuttle in the 1980s and '90s. This educational brief for grades 9-12 provides assembly instructions for constructing a mini drop tower. The drop tower holds demonstration payloads such as a postage scale, a birthday candle, and an oil-drop toy. (MVL)