Notice who hasn't spoken much and invite them into the conversation.
Dinner is often the one time of day the whole family is together. Learning to tell a story, ask a question back or listen to the answer turns that time into real conversation.
Kalmdix announces the mission as a playful quest at the start of the meal, then lets the children talk about whatever they like. It works on one habit over five meals; on the fifth, the mission is a secret. Kalmdix never says who did or didn't do it: the results appear after the meal.