The self-standing unit holds two glass tubes filled with the test fluids, for comparisons and to minimize draining and refilling of the fluids after experimentation. The Viscosity and Particle Drag apparatus is a simple falling-sphere viscometer. The back plate has a low-voltage backlight so students can easily see the test spheres through the fluid. Students fill the two tubes with their chosen test fluid, then select a sphere of the correct density and size for the fluid. They drop the sphere into the test fluid at the top of the glass tube. Students may also make their own use shapes to test in the unit. The apparatus can be used with any fluid that can be safely handled and is chemically compatible with the wetted parts of the equipment - glass and PTFE. The shapes must fit through the valve at the base. Suitable test fluids include water, thin machine oil, castor oil and motor oil.