You can access a student's attendance history from a few different sections.
From the Roster:
Go to Upcoming and click into any roster
Click the More Options [...] menu to the right of a student's name
Select View Attendance to see the student's attendance history for this scheduled activity
From Client Profiles:
Go to Contacts and click into a Client Profile
Navigate to the Bookings tab
Select the More Options [...] menu to the right of the activity name and select Attendance History
From Attendance Report:
Go to Reports, Custom, and click +New Report at the top right
Choose I want a list of Bookings and click Get My Report
Reference the Attended Value column