Twenty years ago when the author was student teaching, he quickly learned what geometry teachers and researchers (e.g., Senk 1985) have long known: High school geometry students struggle with proof. Throughout his career, he has tried to create instructional materials to make proof more accessible to his students. From field-testing materials with…

Suggests having students write short summaries using the principles of the journalistic news "lead" to help them sharpen their abstraction skills. Includes samples of data blocks from which students would compose their summaries, kernel sentences from the samples, "kernel" kernel sentences, first draft summaries, and 30-word…

Recent research literature has highlighted the interest of both teachers and researchers in using analogies to aid students' conceptual understanding. This appears to be especially relevant in secondary chemistry education due to the many abstract concepts that are included in the curricula. This paper reviews recent literature and considers…

Describes the Plane Geometry System computer software developed at the Educational Computer Systems laboratory in Sofia, Bulgaria. The system enables students to use the concept of "algorithm" to correspond to the process of "deductive proof" in the development of plane geometry. Provides an example of the software's capability…