The German Teachers' Association is against a quick lifting of the mask requirement in schools.
Association president Heinz-Peter Meidinger told the dpa news agency on Monday in Berlin that he advised "the greatest possible caution", especially during lessons.
The virus "has not yet disappeared from the scene."
Mask requirement and regular tests should remain in the end of the school year.
Due to the sharp drop in corona numbers, there is increasing discussion in Germany about the mask requirement, especially in schools.
Meidinger said everyone was very happy about the falling incidences and the return to classroom teaching.
However, there are still increased numbers of infections in the group of children and adolescents who have hardly been vaccinated so far.
Risk of a fourth wave
"Around 50 percent of all teachers do not yet have complete vaccination protection." In addition, the risk of a fourth wave cannot be completely ruled out for Germany because of the Delta variant of the virus, which was first discovered in India.
"It is true that masks are a burden for those affected, both for teachers and students, but in the overall assessment we warn against hasty abolition," said the president of the teachers' association.
Federal Justice Minister Christine Lambrecht (SPD) had previously called on the federal states to examine the mask requirement. This is a burden, especially for students who have to wear protection for their mouth and nose for hours in class.