My favorite table manners habit that we have tried to develop with our children (ages 4 and 2 at the moment) is having them ask to be excused before they leave the table. Here are a few benefits:
It’s polite and respectful. Rather than bolting from the table unannounced, they pause to acknowledge their departure.
It makes the meal a discrete event. By doing this habit, the kids learn that a meal is not something that blends together with playing, or with anything else for that matter. When the kids to ask to be excused, they mentally acknowledge that they are concluding the meal and moving on to something else.
You limit food grazing. Sometimes kids will be done with their meal, and then a few minutes later want to eat again. You can use the “may I be excused?” as a clear dividing line between eating and not eating.
You have to enforce this a bit. If they get up and leave without asking, you have to track them down and gently force them to decide if they are excused. This is still sometimes true of our children even though we’ve been practicing this for months.
You also have to stand firmly on the other end and not serve the kids more food after they’ve been excused. This is a bit tougher – it’s difficult to say no to a child that claims to still be hungry. We just tell the kids they can eat at the next meal / snack. They always make it without a problem.
Helping children develop good table manners like this one does take some effort. It’s often worth it though. Establishing ground rules like this can make mealtimes and family life more pleasant all around.