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Chemistry students are better prepared for careers if they learn about the principles of polarity and chemical partitioning that underlie various kinds of chromatography. Principles are more or less the same for paper chromatography, high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC). In science education hands-on activities should illustrate principles. Plant materials, especially colorful leaves such as those of Coleus plants or fall leaves which had been green and then became red, can be used. In a Coleus leaf the pigments represent molecules with a wide range of polarities. First students see a demonstration that results in partitioning of pigments. Later they use their understanding to develop a system to separate different pigments using a rather inexpensive TLC system. They make their own developing solutions. Even advanced high school chemistry students can profit from these activities. The kind of polarity involved with chromatography is not the same kind generally referred to in organic chemistry classes. A football game/music analogy is suggested to help students understand partitioning.

Anthocyanin pigments are commonly used for pH indicators in chemistry courses because of their familiarity to students and their ability to stimulate students' interests in chemistry. Anthocyanins can also be used to explore other topics, such as chromatography, extraction and hydrolysis, to further capitalize on students' natural interests. These experiments are suitable for high school courses because good results are obtainable even when the sample is prepared during a previous class.

Students can use graphing calculators to demonstrate the process of radioactive decay, offering an opportunity to combining chemistry and mathematics instruction. Several activities utilize the calculator's ability to plot three sets of data simultaneously. The results of these activities help students understand the production of radioactive waste through nuclear fission.

Fruit anthocyanins can be used to perform interesting, colorful chemistry demonstrations in secondary and undergraduate chemistry courses because they illustrate light absorption, acid-base equilibrium and other chemical principles. These molecules are responsible for various pigments including red and blue in some flowers and can be extracted from fruit or fruit juices such as cranberry juice. They can provide students with hands-on research and experimentation experience. Suggested experiments are included.

Cooperative, open-ended undergraduate biochemistry student activities involving candies can be used to promote understanding of electrophoretic fractionation on the part of those studying chemistry. Directed activities come first. This could be adapted to biology or general chemistry and even to high school. Students establish the Food, Drug and Cosmetic Identity (FD&C No.) of food dyes used in candy coatings. In the first part of the exercise they investigate electrophoretic mobility of two classes of natural pigments, anthcyanins and betacyanins. The are exploring how and why molecules may be fractionated by electrophoresis. M&Ms, licorice jelly beans, for the open-ended exercises, cranberry or grape juice and beer, which has betacyanin dye, can be acquired at most grocery stores.

Specific gravity or density is easily taught in high school chemistry courses as the ratio of an object's mass in air to the difference between its mass in air and water. However, the concept that this property is intensive in that it does not change with the amount of material is hard to convey to high school students. Three tasks requiring four 50-minute laboratory periods can teach students this principle through cognitively related but physically independent experiments. The experiments can be performed individually or by student groups of two or three.

Chemistry teachers can use an overhead projector demonstration to teach students about acid rain. The demonstration illustrates the production of acidic solutions through the reaction between water and nonmetallic oxides and the impact of bedrock on acid rain. The chemical reactions are started by using a three-well culture plate to produce the acid anhydrides of sulfur dioxide, nitrogen dioxide and carbon dioxide.