Kinderkookkafé -- Amsterdam's only place where children not only get to do the eating, but the cooking and the serving too. Since young Dutch children don't speak much English, you may want to query the organizers about any possible language issues.
Pancake Bakery -- I have yet to meet a kid who doesn't love pancakes, and this is the best pancake source in town. Pancakes come with various inventive toppings, both sweet and savory. Suitably colorful ornaments such as umbrellas and clowns accompany child-oriented meals and desserts. Toys, children's chairs, and special menus complete the picture.
Wilhelmina-Dok -- Though not conceived as a kid-friendly place, this waterside cafe-restaurant does have a few things going for it. You get there and return by harbor ferry, which ought to add some interest to the proceedings. Once there, either outside on the breezy terrace or snug and warm inside, young folks can see barges, ferries, yachts, and other vessels coming and going on the IJ ship channel, and maybe even spot a cruise liner docked at Passenger Terminal Amsterdam. If you have young kids in tow, this is likely a better jaunt at lunchtime.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.