While teachers are interested in new chemical information and theories to include in their courses, the majority of their time is spent teaching well-established concepts and facts. Thus, much of the effort in improving teaching quality revolves around a search for clearer ways to express the standard concepts and for better methods for teaching that more closely parallel how students learn. The papers submitted to this Journal reflect this preoccupation with both teaching new methods and new teaching methods, and this issue contains a wide variety of articles that fit into one or both classifications.

When students perform poorly, teachers often respond by trying to find new ways of organizing the information, new methods for calculating results, new methods for analyzing data--whatever would simplify the learning process without oversimplifying the concepts actually learned. This approach leads to innovations such as Campbell's "Simple Rules for Determining Nuclear Stability and Type of Radioactive Decay" (page 892), which were designed to help introductory students to remember and understand the factors that influence nuclear stability, and "The AC Rule: An Algorithm for Organic Reactions," devised by Kiefer (page 906) to guide his students through the process of of predicting the products of a reaction. Similarly, Bluestone and Yan (page 884) provide a simple method for extracting rate constants for reactions from analytical and simulated data, and Radhakrishnamurthy and Selvan (page 895) show how they teach kinetics and mechanism of electrode reactions using stoichiometric numbers.

Sometimes the learning problem is caused by a rule that is already used routinely being applied in cases that are inappropriate. Straub (page 889) states that overemphasis on the octet rule as the "norm" makes drawing Lewis structures of oxides, oxoacids, and oxoanions a cumbersome process and shows that by assuming that the octet rule only applies to 2p elements the procedure becomes a simpler one. Logan (page 896) discusses another abuse of a commonly used paradigm--the least squares regression analysis. With the advent of easy-to-use computer software packages, the treatment is used ubiquitously and, unfortunately, sometimes thoughtlessly. Logan discusses the cases where the assumption underlying least-squares analysis is invalid and shows the appropriate data treatment under those conditions.

Another response to poor student performance is to investigate how students learn and then modify the methods of teaching rather than the material being taught. It is clear that students new to chemistry do not think about the information they are given in the same way that experienced scientists do; they need to be taught in ways that helps them make the connections between information and the concepts that explain it. Time-tested methods such as demonstrations and analogies still are popular teaching methods to achieve this goal. This month's Applications and Analogies column (page 914) contains a pictorial analogy devised by Crute for showing the difference between energy content and temperature; another analogy, this one for mass spectrometry, was designed by Grim and Sarquis (page 930) for presentation on the overhead projector; and the Tested Demonstration this month is a combination by Proksa (page 931) of two old favorites--the ammonia fountain and the density gradient column.

When familiar teaching methods do not solve the problem, a more in-depth analysis is called for, and perhaps more drastic remedies may be needed. Friedel and Maloney (page 899), frustrated with students' inability to solve problems involving the mole concept, focused on studying how well these students understand the meaning of subscripts in chemical equations. They found that many students in their study didn't realize that the subscript in a chemical formula contains meaningful information when they are working problems, and they suggest implications of this problem and ways to address it. Recently there has been a movement based on learning theory to shift curricula to a performance basis. Wygoda and Teague (page 909) report on the process and details of designing a performance-based course at their high school.