On the Assessment tab, the teacher can see the current Assessment level for the pupils in the lesson. They can also update any levels when needed.

If the pupils are all at the same Assessment Level, Teachers can update them in one go. To do this they need to click the Select All option, then select the new Assessment Level from the drop down. 

Alternatively, they can toggle the pupils they wish to change and then select the Assessment Level. 

Either way teachers will need to click Confirm Update to save those changes.