If you're looking for the best MP3 player for kids, your best bet would be the really compact ones. While there are devices specifically designed for kids, you can also consider the compact ones that aren't necessarily meant for kids.
This MP3 player for kids comes with changeable faceplate, earphones and has Music Express software for creating audio CDs as well as organizing music files and playlists. You have a color choice of blue or pink. Playskool has come out with the “Made For Me” Music Player. This unit is an MP3 player for toddlers. It is made by Hasbro and for its target market it is quite a complex gagdet.
The rugged design will keep it safe no matter what sort of punishment it might get and because of its small size and design, it will fit anywhere. Easily one of the top 5 MP3 players for kids, in my humble opinion.