Which grade are you going to teach? When I taught Kinder, it was all about routines, expectations, behavior for a long time. For many of them it was their first school experience. We took a tour of the classroom, talked about personal space, toured the school etc. We also discussed class jobs, bathroom sign out, noise level expectations, raising hands.. pretty much everything. Now that I teach third grade it's more of a review. We create our class expectations together and write them in a big anchor chart.
I try to incorporate science in other subjects I teach, especially math, reading, and social studies. There are many lessons in social studies that I can cross over especially when talking about regions, landforms..etc. I'm doing and ecosystem project right now that has a lot of social studies integrated with it because of the regions. Depending on the unit, I also find books for guided reading that tie into the science that we are doing either fiction or non fiction.