Audio-visual aids are instructional materials that utilize both hearing and sight to effectively convey information to students. They make learning more concrete and realistic by providing firsthand sensory experiences. Audio aids use sound, visual aids use images, and audiovisual aids combine both. These aids stimulate learning by motivating students and helping them classify and understand concepts. While they enhance the learning process, audio-visual aids also have some disadvantages like requiring proper environments, electricity, and technical support for projection.