This document discusses learning aids and improvised science teaching aids. It describes learning aids as devices like charts, diagrams or notes that help students grasp concepts more easily. It then defines audio-visual aids as tools that help communication and learning. The document goes on to provide examples of different types of visual, audio and audio-visual aids. It also describes several improvised science teaching aids that can be created with low-cost materials to demonstrate concepts like carbon dioxide being heavier than air, factors that influence resistance of a conductor, and electrolysis of water. Finally, it defines improvisation as creating new combinations of existing pieces for a purpose, and provides additional examples of improvised science teaching aids.