I'm an IT teacher from Australia and I use Construct 2. One thing about teaching is that it's not about the technology, but about the quality of teaching resources.
Tutorials, examples, guides, worksheets ready to go. This is how you sell well to the education industry.
I currently use the free version because it's all we require. I did email about the cost for education licence, but haven't heard much.
In Schools in Australia GameMaker is more popular. However the free version doesn't want to run on my lab, likely because of the online updater.
Students love seeing their games in a browser. And uploading them to DropBox is also a great feature.
The balancing act with building games is having tasks that challenge the smart kids but don't alienate students that aren't that much into computers.
So what I do is have several parts to a project. The fist part is building the game. I give them the marking key and a video (fraps recording) of me building the game. But the criteria are very detailed. All the asset names, positions and sizes of sprites and all of that.
To this point everyone is doing well. To then separate the students I have other parts with theory questions and modifications to the game. The mods start off easy with things such as changing the size of a sprite or doubling the score system to hard ones such as adding a bonus enemy every 30 seconds and things like that.
My resources so far have been the tutorials on this website and various YouTube videos. GameMaker tutorials can be also used as the Event-Action approach is very similar.
Feel free to ask me questions!