Presents an experiment that uses thin-layer chromatography to identify various aspirin-free Bayer products and to determine whether the products are in fact aspirin-free. (JRH)

Compares the nature of student thinking in confirmation and open-inquiry laboratory activities. Reports that student thinking processes exhibited in confirmation laboratories emphasized procedures and techniques--making sense of and doing the laboratory, whereas student thinking in open-inquiry laboratories emphasized data analysis--making sense…

Reexamines an experiment in which the volumetric fraction of oxygen in air was supposed to have been determined. Presents challenges to the procedure. (DDR)

Describes a simple audio conductivity device built to address the problem of the lack of sensitivity needed to measure small differences in conductivity in crude conductivity devices. Uses a 9-V battery as a power supply and allows the relative resistance differences between substances to be detected by the frequency of its audible tones. Presents…

Demonstrates some of the chemistry of chlorine on a microscale about the size of a water droplet. Chlorine gas was prepared from an acidified bleach solution in a plastic petri dish. Provides suitable hands-on experience for students at the secondary-school level. (MM)

Describes a method to examine preparations of rocks in thin sections between crossed polaroids using a converted biological microscope or a homemade polariscope. (JRH)

Presents a simple experiment that enables students to get a quantitative measure of the relationship between the resistance of a wire and the temperature of the wire allowing the calculation of the temperature coefficient of resistance. (JRH)

Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)

Outlines the use of the toy popularly known as Newton's Cradle or Newton's Balls in illustrating the laws of conservation of momentum and mechanical energy. Discusses in detail the joint effects of elasticity, friction, and ball alignment on the rate of damping of this apparatus. (JRH)

Presents a procedure to demonstrate how the speed of sound in air or within a denser gas can be calculated quickly and accurately in the laboratory. (MKR)

Describes how Newton's Law of Cooling and the Method of Mixtures are used to solve the basic dilemma of whether to add the cool cream to the hot coffee or to let the black coffee cool down first and then add the cream. (ZWH)

Describes simple, inexpensive activities for teaching students about mutants and mutations in bacteria. Explains how to isolate bacteria from soil and leaves and how to grow bacteria on agar or in broth. Describes how to construct a gradient plate for finding the minimum inhibitory concentration of a substance and how to use this set up to find…

Describes the easy collection procedures and classroom uses of live planarians. Suggests that the use of live animals in the classroom will allow students to observe different biological processes exhibited by living organisms. (ZWH)

Describes simple experiments to explore the variables and links to a theoretical approach. Using genuine data, develops an application to the drive mechanism for a lift in a deep mine shaft; poses follow-up questions. (ASK)

Describes a unit of laboratory work which was unusual in that the teacher's purpose was to develop students' understanding of the way scientific facts are established with little expectation that they would understand the science content involved in the experiments. The unit was very successful from both a cognitive and affective perspective.…