Cool site to practice reading music.
These set of 40 youtube videos would be too boring for a child but if you do not know how to play music it should work for you to learn.
http://www.youtube.com/view_play_list?p=253192EED47525A8
This is a simple explanation of treble clef notes:
http://www.youtube.com/watch?v=3bfl4iAnCEs
This explains the different major scales how many sharps or flats and which notes:
http://www.youtube.com/watch?v=tjH4SFqNKtk&feature=related (sharps)
http://www.youtube.com/watch?v=yGxzH8qbk_w&NR=1 (flats)