Why might the author have chosen to intersperse the conversation in the kitchen with the conversation about dominoes that Ruby and his siblings hold outside of the kitchen?

In the Steiner household, Rudy and the younger children are setting up dominoes while their parents argue with the two Nazi agents in the kitchen about inducting Rudy into a special military school. Rudy eavesdrops on the conversation as the children set off the dominoes by candlelight. I'm guessing the dominoes are a symbol of Rudy's world collapsing once the Nazis want him. There will be reprocussions for his parents refusing to let the Nazis take him.