Laboratory:

Please remain seated until your number is called. Then take your number card, and proceed to the cashier.

Note: For the cashier in the laboratory, oTree can print a list of payments for all participants as a PDF.

Classroom:

If you want to keep track of how students did, the easiest thing is to assign the starting links to students by name. It is even possible to give each student a single permanent link for a whole semester using Rooms; so no need to waste time in each lecture with handing out new links and keeping track of which student uses which link. Alternatively, you may just give students anonymous links or secret nicknames.