Jewish holiday activities for my kid's public 1st grade class?

I'm thinking about visiting my kid's 1st grade elementary classroom to present some activities around Jewish holidays. Some other parents have been doing this for some other religious & cultural holidays, and it'd be nice if my kid (the only Jewish kid in the class) felt included this way too.

(You can argue about how fair it is that some holidays get taught by the classroom teacher and others only get taught if a parent shows up. But as a practical matter, I'm going to get better results if I help instead of asking the teacher to do this by herself, and I don't really mind.)

But I'm really not sure what to present! I'm especially uncertain about where the right line is for an public school classroom when talking about religion.

Surely some Jewish organization has put together some resources for this kind of thing? I'd definitely prefer a prepackaged lesson plan rather than trying to cobble together something myself. Worst case scenario I just bring a book to read from, but even then I could use some ideas on which book is a good intro for non-Jewish 1st graders.