How can I see the school usage and achievements?

Firstly, Click on the School usage button, under the leaderboard menu. Select a date range and this will download an excel report with entire school usage. You will have a tab showing school performance, Classes usage and performance, Teachers usage and performance aswell as students usage and performance. 

Click Here to View a Sample Report

An alternative is to go into snapshot reports and choose "All Classes" (available only for admins) and see the total number of activities performed by each class aswell as the level of performance.

Please watch the video below for further help