Think about it. Amazing Spider-Man: 12, Iron Man: 12, Guardians of the Galaxy: 12, Ninja Turtles: 12, X-Men: 12...and so on.
Since no one at the school is 12, this poses a problem. There are only a handful of PG films, and most of those had to be ruled out due to length (Spider-Man 2, Superman). Batman & Robin was ruled out for other, obvious reasons.
The headteacher suggested looking at animated films, though many of those are problematic too for the same rating reason. There are a couple, I will admit, but not a lot. Then I remembered Flight of Dragons.
Yes, I know, Flight of Dragons isn't based on a comic; it's loosely based on two novels. I figured I could get around this, however, since a) everyone wanted to watch ThunderCats cartoons last year despite that franchise not really being 'comic', b) many so-called 'comic' conventions are actually 'pop culture' cons and it wouldn't be too hard to theme the entire school con around the 80s, and c) it's a really good film that most of the children wouldn't have seen before.
The Flight of Dragons was made by Rankin Bass (who made a number of TV animated films, such as The Last Unicorn and also ThunderCats) and released in 1982. The story is a mash-up of The Flight of Dragons by Peter Dickinson and The Dragon and the George
For it's relatively short running time it's extremely epic in scope; like a Lord of the Rings light. The quest begins with three companions but others join along the way, working together to overcome adversaries. Not to give too much away, but the final battle with Ommadon is very impressive and, dare I say it, a tad scary. There's little in the way of violence, but, well, when the villain shares a voice with Darth Vader... Take comfort in the knowledge that good wins out in the end.
I loved this film as a child. My dad recorded it off the TV when I was small and the video was watched numerous times after that. Due to a lack of an official DVD release, he then put this onto DVD and my children have watched it over and over since. Thankfully there's now a release in the USA which will play worldwide.
Ultimately, while Flight of Dragons is an amazing film, I decided against it for the con. I just couldn't get over the fact that it wasn't comic-based. As something that takes up a reasonably large proportion of the convention running time, the film has to be comic related. The kids will just have to wait for a school screening another time.