It's not about blame, it is about doing better.
Fing hll.
OP. If you’re not going to give basic information what is the point.
*Was the injury severe? For example, broken bone?
*Was the injury moderate? Black eye or cut?
*Was the injury mild? Small bruise or scratch?
*Was the teacher absent for a long time-
Half the lesson, chatting to colleagues?
*Was the teacher away for a few minutes - e.g. retrieving something from the photocopier down the corridor?
*Was the teacher away for less than a minute - e.g. getting a glue stick out of the cupboard next door?
Was the class in the middle of a science or DT practical with machines or chemicals?
Did it happen in P.E.? Did they have the javelin sticks out? Or did the teacher nip in to get their stopwatch whilst the entire class were in the local area on cross country?
Or was the lesson a History lesson with everyone sat in rows?
Does the teacher often leave the class unattended?
Yes, teachers leave classrooms for short periods of time occasionally in secondary school. They don’t have an adult watching their every move at lunch or break either.
What do you want to happen OP?