Grilled cheese at school

I've been considering making a grilled cheese in the morning before school and bringing it. Any tips to keep it fresh and not soggy? I have a thermos, but I'd have to cut it in a weird way to fit it.

Try one of those insulators that pizza places use to keep pizza pies pipping hot while it's in transit for delivery. I'm not sure how long it'll last, but you can have a pizza in one of them for about 45 minutes and it'll still be nearly as hot as when it first came out of the oven.