Plates from coffee cup or tea cup sets are great portions for kids and produce servings.
I portion out some of our fruit and veggie servings for the day on these and they’re also great for kids. The two benefits of using these for kids are 1) they’re unpaired anyway so if they get broken it’s no big loss and 2) it starts getting kids used to heavier and reusable items. Because a lot of these type of plates can be free or cheap if you ask around or shop second hand, they are a great way to implement portion control, plan out balanced meals, and train up kids.