Agenda for the Next Meeting
One way to have a set agenda for your SI-PASS session is to ask the participants in the prior meeting what they would like to focus on during the next session. Either you ask them directly or let each participant write down one item they would like to focus on during the next meeting on a piece of paper and hand it to you, or have a vote on difficult topics you have identified that have been covered or will be covered until the next meeting.
Keep in mind: What is perceived as interesting to work with during the coming meeting might change until the actual session. Check with the participants the day before if the agenda still is OK or be prepared with a plan B at the meeting.