Try rewarding
Answer from Elian on Stack Exchange: giving you a good feeling that you have done something valuable, important, etc.
: yielding or likely to yield a reward : valuable, satisfying a rewarding experience
M-W
Try rewarding
: giving you a good feeling that you have done something valuable, important, etc.
: yielding or likely to yield a reward : valuable, satisfying a rewarding experience
M-W
See heuristic. It means involving or serving as an aid to learning, discovery, or problem-solving.
Another similar word is didactic, which means that something designed or intended to teach people something.
Also, for catchy phrase try "propitious projects."
Propitious means likely to result in success, or showing signs of success. It also means favorably disposed, or tending to favor. The projects you did turned out to be propitious because you learned a lot from them.