How to get duration between different events of user and dash-boarding on it.

Hi,

We send events and certain user data to amplitude. example - start-Activity and then stop-Activity when user start an activity and when user stops the same activity.

Would be interested to know if theres any way I could get users duration of that activity and also view dashboard for various users , adding to that grouped by certain event properties as well.

Example Users can perform “Join-Class” <Event>  - (start Activity), eventProperties (classId,timestamp), “Leave-Class” - (stop Activity), eventProperties(classId,timestamp).

Any way I could get all users grouped by classId and duration of different users in that class performing activity.