2. Encourage your children to eat slowly. A child can detect hunger and fullness better when eating slowly.
It's the same for adults, actually. It takes a bit of time between the time you eat the food and the time you feel it fill you. If you wait until you feel full to stop eating, you tend to overeat.
A piece of advice I've heard that has worked well for me is to always finish meals feeling slightly hungry. Half an hour later, if you're not hungry anymore it means you had eaten enough but just didn't know it yet. If you're still a bit hungry, have a piece of fruit.
Not always practical to do but works for me. (That's advice for adults, though)