Be organised . . . By your attention to and mastery of what may seem to be petty detail the pupils come to realise that this is a teacher who knows what he wants and who means to get it . . .
If you have any say in their provision ask for 16mm rulers. They are long enough for most school purposes, are less easily broken, are more easily carried and do not readily adapt for use as weapons or catapults . . .
If the class is beginning to play up and if you are unable to spot the main offender, give the class some written work to do and move to a position at the back. The troublemaker will probably be disconcerted by your new position and desist . . . you will be able to move about quietly (rubber or crepe soles are an advantage) among the pupils, on the alert, but not giving too much attention to individuals . . .
There is a place for humour in the classroom, but the teacher who seeks popularity by striving to be funny is courting difficulty. It is easy to be humorous at a pupil's expense, but this is harmful to the pupil concerned and in the long run to the teacher. Only when a pupil tries to be funny at the teacher's expense, is it in order for the teacher to reply in kind.
The qualities which give a teacher class control are to some extent indefinable. Some find it relatively easy, others have to labour hard at it.