Reading the same chapter does not mean understanding it in the same way. A study group makes those differences available for discussion. One person can explain a step that another skipped; a question that felt embarrassing alone may turn out to trouble everyone.
Unlike a lecture, the group’s immediate material is often the work its members cannot yet do. Peer-led study groups can connect that work to prepared support, although an informal group may simply consist of classmates setting aside a regular hour.
Showing your working
Imagine three people preparing for an accounting exam. Dividing the exercises and exchanging finished answers would save effort while concealing confusion. Solving a problem separately, then comparing the reasoning, makes the meeting a learning activity. Working in pairs for part of the session can give each person more time to explain their reasoning.
The temptation is to let the quickest person perform while everyone else watches. Taking turns explaining, giving people time to attempt a problem first, and asking where an answer came from can keep competence from concentrating in one member.
A group also needs somewhere to take unresolved questions. Repeating a confident misconception does not improve it. Notes for an instructor, an answer key with explanations, or a trusted reference let members distinguish collective understanding from collective guesswork. The scheduled meeting supplies momentum; the exchange of reasoning is what gives that momentum direction.