Student or Learner
When child did not behave in the class that the teacher asked him to sit away from the class.
1. Shall I say :
He got time out from the class.
2. Can I use naughty or mischievive instead of did not behave?
He's been very naughty/mischievive during the class.
3. How should I put ground time in the above sentene?
In #2 "naughty" is OK, but "mischievious" would be another term, not "mischievive".
In #3 I think you are referring to the term "grounded" which originates from the term used when pilots were forbidden to fly for a period of time as punishment for breaking some rule(s). I would not use the term as a teacher. Rather, it is more appropriate for use by a parent to confine a child to his/her home for some reason as in "You were late coming home last night so you are grounded for two days".