Adding science into your placement would be great! I'd start with topics that are of interest in the class, or what topics your cooperative teacher is discussing. Then look on the learning center for ways you can get your students to ask questions. Once they start asking questions, you can easily find / adapt / design activities based on their questions (or better yet, have them work through to design their own activities) that help them find naswers to those questions.
For example, many ECE classes are still working thematically, and pumpkins are usually covered in October. As a start, you could read Pumpkin Circle, a solid non fiction text, as a starting base for asking how pumpkins grow. Then one possibility would be to discuss what everyone gre in their own gardens (great speaking and graphing activity) and start wondering if their garden plants needed the same as the pumpkin. From there you can go many different directions! Sarah Maynard wrote about pumpkins with Peggy Ashbrook recently in The Science in the Early Years: https://www.nsta.org/blog/pumpkins-inspire-investigations
You can also find lots of other good ideas from Peggy's column https://www.nsta.org/blog/all?keywords=Early+Childhood
There are many other ways to integrate science into just about every topic. Like anything else, the more you do it, the more comfortable you will become