Certified GKH Gardening Expert
It is a bit late, but you can still get a decent enough harvest for them to get the feel of the project. I could also recommend garlic! Most are very cold tolerant, and can be planted in September and October for a good harvest before the summer. Snow and Snap peas are also a fun, and easy project for cool weather.
Here is an article for more information: https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-7/planting-fall-gardens-in-zone-7.htm