Good game
This is one of those games that is challenging because you are not use to doing this kind of articulation so as for game design and origenality i want to give you very hight marks, i would asume this to be on a new brain age or other learning game title.
well done.
as for improvements try to lower the time restrictions a tad but make things a little more dificult, ex: change the backround color/pattern make it harder to find the balls, make bad sphears you can not run over with the keyboard curser etc.
I think you could improve this a great deal if you put your mind to it.