Most of us could relate to the URL and I believe it would make a very lasting impression with the people you are targetting. The interface is pretty dull. I guess it probably echos what you feel what learning is all about. Actually, some color would indeed make it more a fun place to be at. Maybe some forums on things teenagers like would be nice. It doesn't need to be all dull.
nice logo add just a bit of colour, you dont really need to change that much , you have done a good job overall.
lousy design for the name. i reckon a grungey/dark design would look better, that design is too "pretty", and is used on quite a few sites.