Peer-mediated instruction is when two or more students work together to learn something. It's different from when a teacher teaches the whole class, because in this situation, other students help each other learn. For example, one student might help another student practice a new skill, or work on a project together. Peer-mediated instruction is an effective way for students to learn, because they can teach and explain things to each other in ways that make more sense than when a teacher does it.