Presents a classroom experiment that demonstrates the directional sensitivity of the human ear. Outlines the activity's procedures and provides a diagrammatical view of the experimental arrangement. Also included is an analysis of the expected results. (ML)

Briefly describes some of the more recent developments in the use of human hairs for such instructional purposes as observing barr bodies and chromosomes, and for culturing to produce cells of both epithelial and fibroblastic morphology. Three main hair categories are also described. (JN)

A single heartbeat is a complicated process. In Dutch upper secondary biology textbooks this process is illustrated by the classical Wiggers diagram, which usually shows different heart-related quantities, like voltage (ECG), blood pressure, and the heart sounds. It may help students to understand the nature of the Wiggers diagram if they perform…