Are you taking about the people who phone in at the end of the episode?

Yes I’m wondering if it happened IRL :)

It seems unlikely since the callers would have to have somehow seen the episode before it aired.

I don’t mean that- I mean did people call them with questions regarding science and previous episodes? :)

I did some googling and it looks like there wasn’t a published number but they may have called their local PBS station and asked. I think it’s probable some kids asked questions and probably got answers.

Thanks :)