Does anyone successfully use a reward system for positive behaviour and if so, what is it like, does it help etc? We are struggling a bit recently, particularly with our 3.5yr old - although not sure if he might be too young for a system? Our elder child is 6 so also not sure how to do a system that is fair to them both? I'm thinking along the lines of sticker chart or pompom jars then picking a a reward once completed etc.