For k science we did the Evan-Moore Learning to Be a Scientist book. What was most important for me was not that he remember every science fact we covered (and it covered a range of subjects) but that the main concepts about what scientists do was remembered and he could apply/identity those concepts to science he learned in the following years. (Scientists make observations, scientists make comparisons, etc.)
It's a K-1st grade book, and required no reading or writing. The kids had a LOT of fun with it. If you're interested, I blogged about all the lessons. (The search puts the newest posts on top and the oldest on the bottom, so you have to go to "older posts" to see them in chronological order.)