open classroom
noun [ U ] uk/ˌəʊ.pən ˈklɑːs.ruːm/ us/ˌoʊ.pən ˈklæs.ruːm/
（美国的）开放式课堂，大课堂（指开展不拘形式、富于变化的课程或活动以适应每个学生的教育制度）
in the US, a system for educating young children in which classes and activities are informal and changed to suit each child