Teachers and Admins can look at the list of Students in a Student Group and see their Rank, the last level played, the last time they played, and the number of completed chains (times played):
This gives a good idea of a Student’s activity (and there’s a further explanation of Rank here) but it doesn’t give a specific measurement of progress.
The most accurate and reliable way to measure progress is via the spelling test. So long as you do not use this test as a teaching tool, do not share the results with the student and do not give them any feedback at all, you will be able to repeat it down the track to discover what has changed.
You may choose to repeat the test at any time: when the student completes a licence, when you need data for student reports, whenever you need to know what progress has been made.