After attempting, without much success, to bring my science club programming to my current library, I decided to begin incorporating science activities into my regular storytimes. This allows me to bring science programming to my preschool patrons in a way that doesn't require them to come to the library on an additional day for a separate program.
At my previous library, another librarian ran STEAM times for toddlers after their regularly scheduled toddler storytime. I decided that this method would make for a too-long morning for my patrons, so I adjusted my regular storytime and replaced the craft with our science experiment.
I did a standard storytime, complete with rhymes, songs, and of course stories, but for the stories I read two different versions of The Three Little Pigs. At the end of storytime, when I usually introduce the craft, I explained that we would be doing a science experiment instead.
I had three tables set out, and each table had a different item on it: standard drinking straws, craft sticks, or DUPLO blocks. The kids and their caregivers collected a worksheet from me and went to each table to construct a house and then attempt to blow it down. It was really neat to watch the kids and their caregivers working together on this project, and I will definitely do something similar again.