Meaning:
To focus and pay attention to something
Example:
The teacher was angry because the students weren’t keeping their minds on the class.

3.glance

Meaning:
To look at something quickly
Example:
The children kept glancing out of the window to see if the dog had come back.

4. busy as a beaver

Meaning:
To be very busy
Example:
John was busy as a beaver today; he left home at 6am and didn’t return until 10pm.

5. in unison

Meaning:
When people do the same thing at the same time
Example:
When the teacher said they would have to cancel the outing, the children all groaned in unison.