How long is the flight? Have they flown before?
For my son at those ages, the novelty of the plane, and the thrill of my undivided attention was enough. We packed a few favorite story books, I told him a few stories from my childhood (even more fun when it's an aunt telling naughty stories about one of your own parents), we leafed through the airplane magazine and looked out the window. We might have torn out some of the pages and made paper airplanes.
Maybe my child's weird but since I wasn't one to generally bring things to "entertain him", the few times I did he seemed to intuit that this meant that it was a big deal and go a little wild. My mother would bring toys to a restaurant and he'd drop them, play too loudly, fuss if I put them away so he'd eat. If I didn't bring toys he'd just participate in the conversation, daydream or color if the restaurant happened to bring crayons.
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