According to relevant information, Tianjin Education Bureau stipulates that online teaching is not recommended in the lower grades of primary schools, but can be guided by teachers, and parents and students can choose to study independently.

1. Each class in the middle and senior grades of primary schools is 20 minutes, and the online education and teaching time should not exceed 60 minutes in principle every day.

2. Each class in junior high school is 30 minutes, and the daily online education and teaching time should not exceed 120 minutes in principle.

3. Every class in senior high school is 30 minutes, and the teaching time of online education should not exceed 180 minutes in principle. Grade three, grade three graduation can be appropriately extended according to the actual situation.