This book covers the requirements of the current Tanzania Primary School syllabus of Science and Technology for Standard 3. The book uses a simple language and straightforward approach to ensure that pupils understand easily. In addition to its beautiful layout and richness of illustrations, the book has plenty of science activities which will help to develop investigative skills in a pupil. These activities also help pupils to use science to explain everyday activities and phenomena. This book builds on a competence-based approach used in similar books for lower classes. Together, our books equip pupils with fundamental science knowledge and skills in a manner that relates to real life activities.