Besides going to the playgroun, park or library... what free structured activities do you do with your LO?

I'd like to start taking the kids to story time at the library... right now, we just go to the library and read to them for a bit (free but unstructured).

Most of the structured activities that we do require money though: music class is $5 a session, soccer or swimming costs money, etc. It all adds up and I'd love to find free equivalents!

What free structured activities do you do with your LO?