One of the important aims of good biology teaching should be to encourage some basic understanding and appreciation of ecology. This understanding should include not only the scientific basis of ecology, but also its application for human welfare and, in particular, for rational exploitation and management of the natural environment and resources. Many of the problems faced by humanity are basically of an ecological nature: over-population; food production; deterioration of habitats; and pollution of air, water and soil. Thus, to make appropriate decisions related to aspects of human needs such as housing, agriculture, deforestation, industry, etc., an understanding of the scientific process of ecology is essential. It is to promote this understanding among biology teachers and their students that this document has been designed, with focus on simple experimental techniques in the field. The suggested projects or activities cover a variety of habitats, and individual species or their populations in tropical countries. Exercises include: (1) objectives; (2) curriculum links; (3) students' background; (4) students' preparation; (5) equipment; (6) methods; (7) teaching hints; and (8) follow-up. (Author/CW)