Check here for popular songs that Primary School students learning ukulele may be interested to play. They are current (> 2011) and to my knowledge don't contain expletives or inappropriate adult concepts, but that will also be subject to your judgement. The song name is followed by a link to an external chord/lyric page (all care, no responsibility!) one to a video. New entries will be added periodically. Suggestions and comments are always welcome.
adjust the key on the chord/lyric sheet to F
and a Ukulele Underground lesson
On both the uku tabs and UU pages, it's in the original key which is quite tricky, but can be transposed down one semitone (to Am) on uku tabs which makes it much more forgiving!