I would add, cameras in every classroom and hallway. Classroom cameras would be with sound so parents could also see what is being taught to their kids.
OH you are SO on point! When i was a student nothing was thought or said about parents monitoring classes at any time. Parents were invited! When my children were in school I made it a point to assert my right and monitor classes from time to time. I had to insist/fight to do it, was not disruptive in classes but not welcome. When my older grandchildren were in school parents were not allowed so older daughter became a volunteer teacher's aide so she could monitor and be abreast of the teaching. The younger grandchildren are awash in a socialist system of leftist learning that must be counteracted at home. (Dad is active military, mom is primary breadwinner due to low enlisted salary so no home school feasible)
IMHO If teachers are so leftist they refuse to carry guns in school they shouldn't be teaching. My grandchildren are worth having their teachers armed. I think a properly trained individual can determine when/where to get kids safe and when to fire. Just my $.02