Students learn that light travels in straight lines and that rays of light can be reflected by shiny objects or bent by lenses. They also learn that sight depends on light. Students learn that people make sound when their vocal cords vibrate and that people use sound to communicate.
Students also learn how people hear sounds.
Students then explore how other living things make and use sound to communicate. Students learn that sound is made when matter vibrates. Students learn how volume differs from pitch, and they explore what things around them can make sound. Students learn that sound travels through different types of matter at different rates and that echoes occur when sound bounces off certain type of surfaces. By the end of fourth grade, students will develop an understanding of light, heat, and sound.