Discusses the possibilities of toxins present in medicinal herbs. Describes an experiment in which toxic constituents can be selectively detected by thin-layer chromatography and NMR spectroscopy. (TW)

Discusses the uses of thermistors in teaching electronics and semiconductors. Describes how to experimentally measure and graph the characteristics of a thermistor. Suggests one possible approach to understand the shapes of the characteristics. (CW)

Explains the use of an accelerometer in investigations confirming Newton's second law. Provides diagrams and descriptions of the apparatus. (ML)

Discusses the velocity of an orbiting satellite. Knowledge of the kinematics of falling objects is the only prerequisite for understanding the concepts considered. (DH)

Describes a comparison of scale of laboratory with respect to time efficiency. Compared full scale and one-tenth scale Grignard reactions with full scale averaging 330 minutes to completion and scaled-down averaging 204. Savings are seen in air pollution, toxicity, solvent cost, and time. (JM)

Describes use of a Fresnel biprism to demonstrate double-slit interference with polarized light. Discusses polarization and phase properties of a randomly polarized gas. (JM)

While students are able to cope with the slide-wire Wheatstone bridge, the slide-wire potentiometer has had a long history of confusing and frustrating elementary physics students. Therefore, a new approach for teaching and using the potentiometer has been developed. This approach is described. (JN)

Investigated the role of "a priori" ideas in planning experiments and data processing leading to inferences. Thirty-one students (ages 11-13) observed a "combustion/candle in a closed container" experiment and were asked to interpret sets of measurements. Findings, among others, show that children preferentially experiment on…

Provides a detailed description for the construction of equipment needed to investigate acid/base equilibria through the measurement of pH and potentiometric titrations. Suggested experiments and calibration techniques are explained. This information helps to solve the problems of inadequate, expensive equipment required for A-level chemistry…

A hair dryer, plastic funnel, and microscope slide can be used for predicting pollen counts on a day-to-day basis. Materials, methods for assembly, collection technique, meteorological influences, and daily patterns are discussed. Data collected using the apparatus suggest that airborne grass products other than pollen also affect hay fever…

Describes a quantitative evaluation of an interactive videodisc program in which students measure the temperature dependence of the solubility product of lead chloride by titration of chloride with silver nitrate using a Mohr titration. Student reaction (based on responses made using the program, quiz answers, and laboratory performance) was…

Chemistry students selected a main group of the periodic table, researched the group, and then presented a 70-minute lecture on the group; conducted two lecture demonstrations; and performed two laboratory experiments. This was done to determine what descriptive chemistry should be included in a new sophomore-level inorganic chemistry course. (JN)

Discusses the rationale for using photochemistry to merge descriptive chemistry and molecular orbital theory in first-year chemistry courses. Includes procedures and safety information for various activities, demonstrations, and experiments involving photochemical reactions. (DH)

Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

Background, procedures used, and typical results are provided for an experiment in which students carry out the necessary measurements on the acid-catalysis of penicillin in two hours. By applying kinetic theory to the data obtained, the reaction pathways for the hydrolysis of potassium benzyl penicillin are elucidated. (JN)