Teachers do not need to be supernatural in their efforts to avoid negligence; they simply need to exercise common sense and cultivate effective safety habits. Accordingly, teachers need not restrict their teaching activities unnecessarily solely out of fear of being sued, as long as they exercise "Due Care".
Due Care for a teacher can be summarized in three duties:
The duty to instruct
The duty to supervise
The duty to properly maintain equipment
These three duties form the basis for avoiding negligence. A failure to perform any one of these duties properly can result in an accident, in which the person injured may ultimately blame and successfully sue the teacher and/or school district.
From "Safety and the Law" from the Minnesota Department of Children, Families, and Learning.
If you can reasonably foresee the consequences of what you are about to do or not about to do, you will be held responsible.
The above information is provided for reference only.
Please check with your School Administration / District,
local, state, and federal laws for specific safety information and policies.