PH represents the acidity or alkalinity of any water-based solution. Cabbage contains a chemical that changes color with pH. Some kitchen chemistry results in a home-made pH test paper prepared from red cabbage. The real fun begins when a student finds liquids to test. Vinegar, lemon juice and tap water serve as a good starting point. More ambitious students could run a small-scale environmental testing operation by sampling local rivers, lakes, streams and rainwater.
With a few modifications, a 2-liter bottle makes an impressive water-powered rocket. The aspiring rocket scientist can construct a rocket and launcher from parts available at any hardware store. Alternatively, water rockets sold in toy stores will suffice. Scientifically, water rockets demonstrate Newton's third law of motion -- that for every action there is an equal and opposite reaction. More advanced students can conduct trial-and-error launch trials to determine the combination of water and air that results in the highest altitude.
The term "salt" applies to more than just table salt. Technically, it refers to any compound consisting of a metal and a nonmetal. Many salts dissolve in water, but this process is reversible. That is, students can grow solid crystals of salt from salt solutions. Readily available salts such as table salt, also known as sodium chloride, or Epsom salts, also known as magnesium sulfate, work well. Students can adjust and determine the influence of various parameters, such as temperature, amount of dissolved salt, and type of salt, on the size of the crystals.
Paper has become so ubiquitous in modern society that few people stop to wonder how it is made. In addition to learning the fundamental principles behind paper making, such as the nature of pulp and fibers, students get to use their imaginations in their quest to construct the "best" paper. The list of materials that students can make into paper is lengthy and includes dryer lint and grass.