This will take a bit of work on your part...
check out the NIEHS website, click on Fun and Games, then on Songs and Children's songs.
There are quite a few with MP3s. here's where the work comes in, you or someone will need
to figure out the chords for the songs... most likely in the Key of C, unless she learns other chords
Since the Holiday Season is coming up fast, you may want to get a Holiday Ukulele Songbook and
simply circle or highlight the main chords that will help her play the songs and the chords she knows.
Of course, not every song will be in the Key of C, so you may have to transpose the music for that.
it will be a good challenge for you and for your assistant
keep uke'in',