The teacher should not always stand at the front in class: 

~he/she will not notice which learners are not participating

~it is advised to give activities that will engage every learner.

~teacher to move around the class  to individual learners, or pair, or group activities, giving guidance, acknowledge, answering questions, and offering suggestions to those in need.

Learners should not  always work in silence: ~

~it is difficult to notice if there is learning taking place. Others could be reading something else.

~allow learners time to discuss, consult, among themselves. It could be in pairs, or groups.