We finally did the "Peaches Today" problem on nrich, (nrich.maths.org/2312)suggested by Noble, and my ds really enjoyed it. (But I wasn't sure Q3 was actually right or wrong, since it looked like open ended and you can do what ever you like.)
Anyways, even we love nrich site very much, I struggle to navigate it.
Do you have any suggestion on problem your children/pupils enjoyed?