Describes an experiment that measures the diffusion of ions in the liquid phase and shows that the relative distances of diffusion are related qualitatively to the inverse of the mass of the solvated ion. Involves soluble salts on opposite sides of a Petri dish diffusing through a layer of water and meeting to form an insoluble salt. (JRH)

Describes an experiment that uses air to test Charles' law. Reinforces the student's intuitive feel for Charles' law with quantitative numbers they can see, introduces the idea of extrapolating experimental data to obtain a theoretical value, and gives a physical quantitative meaning to the concept of absolute zero. (JRH)

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)

Presents an experiment that demonstrates that common substances, whether or not the students think of them as medicines, drugs of abuse, or foods, have toxic effects on Daphnia. Combines an inexpensive hands-on experiment with extensive discussion to help the students think about chemical concentration, potency, and the difference between harmful…

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)

Investigates which factors are important in revising chemistry laboratory experiments to enhance student interest and enjoyment of experimental science. Findings indicate the importance of several factors including varied content, real-world connections, items from outside the student's usual range of experience, well-paced experiments, error-free…

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…

Presents one way to use an organized approach to investigation in order to compare and contrast different paper towel brands for their absorption capabilities. Uses investigation procedures rather than formal experimentation procedures due to the nature of the investigation. (Author/MM)

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)

Uses a commercially available meat tenderizer for the source of an enzyme that can degrade meat protein and asks students to test the effects of incubating human hair in water with or without this enzyme. Teaches scientific methodology and the importance of experimental controls. (Author/YDS)

Presents a demonstration of sublimation, in which a solid is directly converted into the gaseous state, using an overhead projector. (MKR)

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 experiments for isolating and detecting siderophores produced by bacteria or fungi. (MKR)

This article describes a science learning experience in which intermediate grade students launched balloons with attached postcards to study wind currents. More than 200 (of over 900 balloons) were returned, and their analysis supported the students' hypothesis about the direction of wind currents. (DB)