Xuetong is an online learning platform, and open class is a course form in Xuetong. Open class refers to the courses provided on the learning platform, and anyone can join it freely. Different from traditional offline classes, open classes can learn independently according to learners' needs and time, and there is no fixed time and place limit for classes. Learners can learn through online videos, textbooks and homework, and communicate and discuss with other learners. Open classes are usually designed and directed by one or more teachers or experts.

The characteristics of open classes are:

1. Autonomous learning: Learners can learn according to their own learning progress and schedule, regardless of time and place.

2. Resource sharing: Learners can get rich learning resources through the learning platform, such as course videos, teaching materials, exercises, etc.

3. Learning interaction: learners can communicate and discuss with other learners and teachers online, ask questions and share learning experiences.

4. Flexible evaluation: Open classes usually evaluate learners through homework and tests. , so as to understand their own learning progress.

By offering courses, learners can learn in a more free and flexible way and improve their knowledge and skills.