Make sure to teach your children to chew food with their mouth closed.
My table manners are perhaps shy of impeccable. I tend to mess up tablecloths, occasionally use the wrong utensil, rarely bang the inside of my teacup with my teaspoon, etc., but I do not chew as though I wished all of my dinner companions would have a good view as to the progress of food mashification inside my mouth.
My friend and I set a lunch date in a fancy restaurant somewhere in Makati. She told me that she will bring her boyfriend. Thought it's gonna be a nice get together, it was a nightmare! Her boyfriend is chewing louder that I have ever heard anyone chew. It's as if he was receiving pleasure in hearing his own tongue slap his food around in his humongous and cavernous mouth. I could hear every frigging action that was occurring in his mouth. It was the most off-putting thing to sit and listen to while you are staring at your own dish.
I actually intentionally stared at him for close a minute to see if he would literally shut up. He didn't. He had no clue whatsoever that there was anything wrong. I wanted to run over and shake my friend violently and ask her how could she possibly face a lifetime with someone who created more sound with his mouth, without speaking or shouting???
Closing your mouth while chewing prevents your food from falling back out. But closing your mouth also keeps chewing sounds to a minimum.