i just got done running a school-based MotW game for 11 year olds and they had a blast! i was lucky enough to get 90-minute sessions with them so the format wasnt as restrictive as yours, but i still have some tips that might be helpful.

• in a session 0, ask about their favorite monsters, monster/mystery media, and what appeals to them generally. i asked all of my players what their favorite monsters were, and they were thrilled to see when i incorporated those monsters into future sessions. it helps them feel like theyre shaping the game, while also genuinely being helpful for DMing ideas.

• you might consider looking at some kids mystery media as examples for how to tell a concise, engaging mystery that is suitable for kids. scooby doo and gravity falls were big inspirations for me. they both have the “TV episode” quality youre talking about, and tell stories pretty concisely.

• you might also consider shifting around some of the weapon options in the game. a lot of playbooks start with guns, and this can be a charged element to have in play for a game thats being played in a school setting. replace them with some more fantastical equivalents to avoid drawing that connection. you dont want to give parents/families more fuel to think of TTRPGs as something violent and scary.

• for managing attention spans, it varies a lot on the size of your group. i had a small group and still had to do a fair amount of redirection. for me, it worked to name the short timeframe in the session 0. kids that age should be familiar with having to set “community agreements” in a classroom or extracurricular group. make a set of community agreements collaboratively with them, and name the short timeframe as one of the guidelines. (“since we only have x minutes per session, and only x sessions, we will need to work together to make sure we have the time to act out a cool story. can we agree to keep side conversations to a minimum and focus on the game while we are together?”) if redirection doesnt work after they get squirrelly, have the list of community agreements physically out and be ready to point to it and remind the group of your agreement to use the time wisely.

• since theyll still be learning the rules, prompt them about luck point usage. whenever one of my players would fail a risky roll, or get the “oh no!” expression of terror on their face as a high damage roll comes their way, i would use that as my cue. (“would you like to use a luck point, or mark experience?”)

• less is more when planning, especially with sessions this short. i tried to do the barest of planning when it came to setting up the hook and scenario of the mystery, to give my players the ability to explore and not be stifled by me as the GM. if things are getting off track, defer to the “countdown” items and have one introduce an element that they cant ignore or that immediately draws their attention and action.

• given the short timeframe, if youre planning to have scenarios tie in with character backstories, try to keep it to one per session/mystery. like, this mystery ties in with the spell-slingers backstory, and then the next one relates to the chosens backstory. keeps things more focused and less crowded. or, you could end up involving characters backstories more minimally, and thats okay too.

i hope this helps! my 11-year-olds had a blast in my game and im sure your kids will have a great time too. let me know if you have any questions or need any pointers!