The Montessori school that my kids attend goes through middle school (7th/8th grade), and they have a Friday Speaker series, where parents come in and talk about their career or hobby or what have you. I've been doing one about tabletop role playing games since 2012 or 2013, and its always a lot of fun. I've learned a few tricks along the way too.
Its a one hour deal, and there are usually about a dozen kids involved. So the challenge is to run a fun demo game within that time period, and being able to engage that many people.
Some of the kids involved have played tabletop RPGs before, some aren't even certain what a "roleplaying game" is. Turns out they've all seen Stranger Things, when I mentioned instances of D&D and rpgs in current media.
I brought a stack of game books in order to show folks that there are games for every interest, mystery, sci-fi, fantasy, etc, as well as very simple games, like the one-page Laser & Feelings, and the light weight Fate Accelerated, to more complex games like Shadowrun or GURPS.
We quickly get to playing our demo game. I put a bucket of dice on the table and hand out some character sheets (those sheets, zipped). They're very simplified, in order to not have to spend much time worrying over mechanics and system.
I've found that what seems to work best is having an engaging initial setup that provides some exciting adventure and lends itself to the party being split up to approach the goal in parallel. This year they had gotten information about the evil wizard Varyx, who was holed up in his skull mountain fortress, working to complete a ritual that would summon armies of undead. I'd decided to offer a few avenues: they could talk or sneak through a mercenary camp, go through a haunted and forgotten underground tunnel, climb the side of the mountain past the wyvern guardians, or fly on giant eagles through a magical storm and shadow wraiths. I steer them toward splitting into three groups of four, and deciding how each group wants to approach.
We had one group do the giant eagles and magical storm, one decide to scale the mountain, and one go for the forgotten tunnel.
My overall approach is to start one group, describe their journey, throw some complication or attack at them, ask them how they're going to deal with it, and then tell them that we'll come back to them. I then turn to the next group, describe their journey, throw a complication, and leave them hanging and move to the third group, do the same, before coming back to the first group and asking them how they plan to deal with the problem before them. It takes a couple of minutes to go around, so usually by the time I get back around to a group, they've had four or five minutes to think about what they want to do, so usually they have a plan. I let them describe what they want to do, if necessary, try to frame it correctly in scale or scope, and then ask them to roll dice to see what happens.
If they get a full success, I let them narrate what happened, only providing guidance if they seem hesitant or if they get well outside the scope or scale of the roll. If they roll a failure, I try to make it an interesting complication. Maybe not a simple failure, but instead a success, but that something unexpected happens -- a cleric tried to blind an approaching wyvern, but rolled a fail. He and the wyvern were both blind!
I end up going around the table a few times. For this adventure, I'd basically planned that most of the action would be in the approach to the mountain. The characters flying on eagles battled against shadow wraiths, and then a particularly strong wind that threatened to blow them out of the sky, and finally against evil henchmen with ballista atop the mountain and an evil cleric. Those going through the forgotten tunnel had to deal with the ghosts of the miners who had been sealed in centuries ago. They then had to deal with a huge stretch of booby traps, and finally with a snake infested tunnel up into the mountain. This group rolled well against the ghosts and booby traps, but had failed roll after failed roll against the snakes. Finally I narrated the snakes clearing the way, but a snake with glowing eyes caused them to glow red- this was a complication which I was really unsure about, as I was running out of time and needed them to get through the tunnel and into the mountain to finish the game, but it worked out great because when they met back up with the other parties, it turned out the red glow caused the other characters to think that they were evil, and for a moment it was tense, before someone removed their curse. The party that went up the side of the mountain had to deal with perilous climbing and with wyvern nests. They had a mix of successes and failures, dispatched a dangerous young wyvern and blinded another, eventually making their way up to the top of the mountain, having to fight through a final dangerous wyvern guardian near the top.
Once they were all through those perilous passages, we were nearly out of time, and I was pretty much out of material, so I narrated them making their way through the skull mountain, had the little bit about the party who glowed red, and then they had to figure out how to get into Varyx's ritual chamber, which they did and rolled some dice. Again, we were mostly out of time by now, and I'd planned that their confrontation with Varyx would just be a short bit, so they cast a spell to open up a volcano beneath him, which was a mixed success, but it stopped the ritual. Varyx fled, and they had to deal with standing atop a crumbling floor over a volcano. They cast a teleportation spell to get away, and we were done.
I'm always anxious leading up to those - a bit of performance anxiety, but they always end up going really smoothly and are super fun.
I have an idea about trying to be certain that every player gets enough opportunities for dice rolls that they can get a complete success and narrate the result themselves. To do this easily, I'd need to mark the players who have already gotten a complete success. I may grab this set of coins online and give one to each player who gets a complete success, and let them keep the coin. I have each player also take and keep a dice of their choosing from the big bucket o' dice.