While small, student-led discussion groups are the core of the Book Club program, discussions involving the entire class also play a crucial role. During community share, students introduce the ideas and issues that they discussed in their book clubs to the full classroom community. Children in other groups who are reading the same book or a thematically related book can share their unique perspectives and knowledge. Community share is also a context in which the teacher can provide instruction that applies to everyone in the class. For example, if a teacher notices while monitoring small-group discussions that many students seem confused about a particular issue, he or she can clarify this issue during community share. The purpose of community share can vary depending on when it is held. A whole-class discussion that takes place before students begin reading can be used to build background about the historical context of a book, or to activate prior knowledge so that students make full use of what they already know as they read new material. Community share can be used to give students ideas about what they could talk about in their small-group discussions. Book Club teachers usually bring the whole class together after students have met in their small groups to allow them to share some of the most interesting ideas to grow out of the student-led discussions. In general, whole-class discussions involve students in a wider community of readers and allow them to benefit from the work of all their classmates.