The teacher assigned a topic for students to discuss.
Tips
usage
课题 is primarily used in academic and research contexts. 研究课题 (research topic/project) is a very common collocation. In broader use, it can mean any significant problem or challenge that needs to be addressed.
usage
Compare: 课题 (research topic/task), 话题 (huàtí, topic of conversation), 题目 (tímù, title/question/topic of an exercise).