My advice, be careful, just because you have not signed anything doesn't mean it won't turn nasty if you do post them.
In short you own the copyright, you may verbally or in writing be giving them a 'licence' to use the images themselves but that's a separate issue.
Are they going to publish them? or are they hoping just for the high res files so that they can sell them on mass for £17 each. This is a common story...
In short if you want to publish an image get a model release from that person and check against the college finally before doing it, only if however its in school time, on school grounds, or shows clearly the school as an event.
Hope this helps.
Tim.
Ambient Life - DCM Gallery
Ambient Life Web Site