I think you asked a fantastic question. I will also be graduating as an elementary teacher and also do not have much experience teaching science. One thing I have learned in classes about keeping students engaged is that you have to make personal connections and get to know the interests of your students. If you can find lessons and activities that your students have interest in, you’ll have a much easier time keeping them engaged. While having every activity relate to student interest is not always possible, you’ll also have success keeping students engaged if they can see you have genuine excitement for the subject matter. Another way to keep student engagement is to relate the lesson to their personal lives. If students are able to relate a lesson to their daily life, the learning will be more meaningful and you will have better success keeping students engaged. Hope some of these tips help!