The editor knew him, because he'd submitted several pieces of work on spec, some of which the editor had used. So the editor knew that my student could write and produce publishable work.
It's so easy to give up. It's so easy to become despondent when a manuscript is returned. We spend so much time putting our thoughts and efforts into producing a piece, it is so disheartening when an editor says 'no'. But that time is only wasted IF we just shrug our shoulders and give up. However, writers who pick up their pen once again, or switch on their keyboards, will use the experience in which to grow as a writer.
So instead of working on just his assignments, this student has written other material and had confidence in submitting his work. Yes he's had rejections, but he's also had several successes. But he wouldn't have had an editor commission him if he had given up.
Keep persevering and it will pay off. You too could get that phone call from an editor asking you to help him out. And that feeling is one of the best in the world.
Oh and John - well done, by the way.