By which I mean, interesting games or websites that children can use and that will hold their attention. Preferably at least semi-educational. I’ve been stumbling through online games but they all appear to be either too violent or too hard.
Any suggestions much appreciated.
Have you looked over Orsinal’s site? You don’t say how old the children are? 
They quite like drawing and creating stuff (which kids don’t?), so stuff like bonomo or artpad would be quite useful too.
Here’s a boatload of Pointless Sites
I encourage my students to go to freerice.com. Mostly I do that because they need to practice their times tables though.
If they are old enough, this game is fun and educational.
Fantastic Contraptions
ETA: This too, Line Rider.
Thanks guys! That rice one is quite interesting, I’ll have to try that one.
I’m trying to think how long I’ve had this bookmarked. I think my son was probably 8 or 9 when I found it. He’s 11 now, and enjoys building and spatial relation type challenges.
That freerice website is wonderful. Thank you so much!!!