Looking for ideas

The teaching garden in the park has had good crops of beans, and the early tomatoes were fine, and most of the flowers (the ones that weren't accidentally weeded) did well. The kids liked those, especially the flowers. (The rest of the tomatoes find it too cool to ripen, and the peppers are slow.) Carrots don't grow very big, but the kids recognize those. (One had been sure that carrots came from the store.)

But while onions and radishes grew very nicely the kids had less than no interest in them, and they don't believe that anything but iceberg is real lettuce. Squash looks weird. They'll take home bags of greens sometimes. The adults haven't been coming by much.

As you can see raspberries or apple trees are out of the question in the small containers, and for teaching purposes I think we want annuals anyway. A few weeks after the kids do the planting we have to have a little lesson on the how and why of thinning.

Any suggestions for kid-friendly zone-5 crops?

Before you get the wrong impression, my wife does the lion's share of the gardening and teaching over there; I'm an occasional auxilliary to do heavy lifting and try to show kids how to wash carrots.