Can I return to my previous selections of students and courses?

Yes, teachers can find their previous selections in the Teacher agenda:

Information System Teacher Previously used selections

Selections are automatically regenerated once every 15 minutes if they are being used. A selection that has not been used for a long time is updated when the "Use this selection" button is clicked. The history is limited by time (six months) and by number. Only a limited number of the most recent selections are available to the user.