A very interesting game!
What caught my interest was the fact that all the marbles had to land in their corresponding goal blocks at the same time, which meant that as more marbles were introduced, the difficulty escalated nicely.
The game is very clean, but the instructions were unreadable (at least for me). If they had not been rewritten in the comments box, I would be lost.
Which brings me to my next point that if a game uses the pointer to interact with objects, their movement should be done with the 'WASD' keys mainly because of player comfort. The send button could then be moved to be 'X' or even the space bar.
Other than that it was a very entertaining game and I wish you good luck with future student projects. :)