Student prizes!

Passports, stamp sheets, points for participation--they can fill them out as they go

Games like trivia, scavenger hunts, or monthly challenges

Students sharing with students--idea sharing, discussion board, or sharing on a Google Doc

Give prizes for attendance using CCSL attendance spreadsheet

Use a Leaderboard or Passport/Bingo fill-in, or Prize listing to build excitement

Do fun Monthly Challenges Or periodic fun 'Question of the Day' on a fun science or math topic (one question, or short list of questions)

Post a Sharing Board (Word or Google Doc) for students to share their MSO experiences in Sessions, cool things they learned, or whatever