Reports on a 30-year-old longitudinal study of reactions in gels. Described are reactions and crystal growth in silica gels and diffusion studies of the Liesegang ring formation. Color photographs showing the reactions and graphs upon the diffusions are presented. (YP)

Summarizes the development of the Earth's age calculation including the work of Archbishop Ussher, James Hutton, Lord Kelvin, Ernest Rutherford, Bertram Boltwood, and Arthur Holmes. Describes the changes in radioisotope dating methods. (YP)

Describes the working of an exhibit in the Ann Arbor Hands-On Museum in which separated water drops from two nozzles collide to make interesting shapes. Discusses the calculation of the vibration frequency after the drop breaks away from the nozzle and the effect of drop size and surface tension on this frequency. (JRH)

Describes the design, development, and validity of the Force Concept Inventory (FCI), a test designed to assess student understanding of the most basic concepts in Newtonian physics and to evaluate the effectiveness of instruction. Discusses various uses of the FCI and the interpretation of the FCI score. (JRH)

Describes the factor analysis and validity of the Force Concept Inventory (FCI), a test designed to assess student understanding of the most basic concepts in Newtonian physics and to evaluate the effectiveness of instruction. Discusses problems in the use of the FCI and urges caution in interpreting and using FCI scores. (JRH)

Explores reasons why students take introductory physics courses at the university regardless of their Advanced Placement (AP) exam performance. Briefly describes the nature of AP physics, the examination format and reporting of scores, and the results of a survey of physics departments regarding their policies towards AP exam scores and placement…

Discusses the use of a spreadsheet program to vary the parameters in multiloop circuit problems. Enables students to better understand how the elements in a multiloop circuit determine the current by allowing them to see the results of the changes immediately. (JRH)

Describes how a simple radio homing device can be used to allow students to participate in a search and rescue mission similar to that which the Civil Air Patrol engages in when locating planes that have crashed. (ZWH)

Provides an introduction to the cubic equation and its solution along with its application to van der Waals' equation of state. (ZWH)

Describes various demonstrations that illustrate double refraction and rotation of the plane of polarization in stressed, transparent plastics, with the consequent production of colored designs. (ZWH)

Identifies some of the erroneous and misleading statements discovered in the three-volume middle and junior high school integrated science text, SCIENCE Interactions. (ZWH)

Describes an experiment designed to help understand the effect of the curvature of the laboratory equipment support (cylindrical rod instead of knife-edge) on the frequency of oscillation of pendula. (ZWH)

Observations of high school physics students in an instructional experiment with an interactive learning environment in geometrical optics indicated that students in the Optics Dynagrams Project went through major conceptual developments as reflected in the diagrams they constructed. (Author/MKR)

Tensile and compressive forces in planar trusses can be analyzed using either the method of sections or the method of joints. This article summarizes and extends a project accomplished by a high school student using the method of joints and graphing calculators, spreadsheets, and matrix-manipulation software. (MKR)

Presents exercises that analyze the additive property of energy. Concludes that if a body has more than one component of energy depending on the same physical quantity, the body's total energy will be the algebraic sum of the components if a linear relationship exists between the energy components and that physical quantity. (JRH)