Kido'z is a new web broswer for children, along the lines of the Zac Browser or Kid Zui. It is free to download and ad free. (It is in beta so the coast may change.)
Kido'z runs on Adobe Air and has a smooth clean interface that would make it great for touch screens or interactive whiteboards. There are three main areas: games, videos and websites.
Unfortunately it is not switch accesible, tab/enter does not work nor do the arrow keys. Supposedly it is for children ages 3-11, but I would stick with the 3-7 year old set in order to account for age appropriateness.