Good science teaching must be based on observation and experiment. There can be no substitute for these. But performing experiments and learning to make close observations require special facilities, and these are lacking in many parts of the world, particularly at the elementary and secondary school levels. It is the purpose of this book to demonstrate how effective experiments in science can be devised and carried out by means of simple and inexpensive equipment. To fulfill this purpose, science teachers from many countries have contributed their knowledge and their suggestions. The book contains instructions for the making of pieces of simple apparatus from materials usually found in almost any region. It also presents a wide array of science experiments from which the teacher may select those most suitable for providing the observations upon which true learning is based. In brief, it has been designed to further the trend of improving science teaching in schools everywhere by basing it more and more on observation and experiment. The book has been planned for a variety of uses: as a practical handbook for teacher-training courses, as a source book for science teachers or for science club activities, as a basis for workshop study conferences in science teaching, as a guide to assembling a loan library of science-teaching kits, and, in general, as a model pattern of science materials and activities for many countries.