{Update: I've created a simple book complete with "illustrations" and resource list for anyone wanting to start their own primary or kindergarten weekly science program in their classroom. Totally free--unlike so many things on the web for teachers these days. Simply click and print the pages you want.}
I'd have to do more digging, but I believe it was in 1995 when I began to do weekly, science mini-lessons with the kindergartners. It was a challenge presented to me by my principal (Cathy Mink) and teacher (Tracey Martin).
"What's something you could do to enrich the kindergartners' experience and provide personal growth for yourself?" Or something similar to that.
What happened first--the purchase of the pictured children's science books or the idea? Who knows. What I do know for sure, is that I've accumulated and refined my library of science books and supplies in the last 17 years.
A few of the other kindergarten aides (who have come and gone over the years) were interested in hopping on the "science wagon" with their students and others weren't, but those I've collaborated with have helped me with the fine tuning. Particularly the aide, Kim, I partner with now.
Our focus is on activities that can be prepped ahead of time, completed in 30 minutes, and are appropriate for 5-6 year olds. We try to coordinate with what's being taught in the classroom or the seasons. Our teachers appreciate us taking this on, so they don't dictate what we do each week. Though, including science journals at the end of all activities (unless we watch a video) began at the request of a KG teacher 15 or so years back.
My current teacher has been talking about retiring, which has caused me to reflect and remember that the teacher who takes over next may not even be interested. And that's okay. It's been fun and educational. How else would I ever have learned about cow magnets? :>)