It would take time to cope with the consequences of the coronavirus pandemic, the KMK said, but "it is still indispensable to keep the schools open and to ensure in-person learning there in the long term", reports Xinhua news agency.
Meanwhile, "regular (Covid-19) testing of students can continue until further notice", the Ministers noted.
The federal state of Saarland was the first to relax health regulations in schools last week.
Bavaria and Berlin followed suit earlier this week by easing face mask requirements for students.
Covid-19 outbreaks in German schools "increased very significantly again between the beginning of August and mid-September 2021", according to the weekly report of the Robert Koch Institute (RKI) for infectious diseases.
It said that 481 outbreaks in schools were reported during that period.
The number of daily Covid-19 infections in Germany increased by 300 from last week to 10,429 new cases registered on Friday, the RKI said.