This is something teachers in ALL grades grapple with! How much do I teach? What it too little, what is too much?
The first person I would go to is your cooperating teacher and other Kindergarten teachers. They have taught this curriculum and should have a good idea of the expectations and will likely fill your bag with all kinds of goodies they have used. Next, look at the curriculum support documents. There should be resources that have been identified or created by the ministry of education to help you out. These would include activities, lessons and assessment strategies like rubrics. Check out your state or province's science teachers' association for their resources. These will be linked directly to your curriculum. Develop a PD plan in which you attend and participate in as many opportunities to learn, network and share ideas about your curriculum.
Don't be too afraid to over-reach your students' abilities. There is a wide range of students in your class, and some of them might understand what you are teaching. Regardless, it is probably better to back track to simpler stuff than underestimate your students' ability to comprehend the content. Reflect on everything you do and make a self-assessment of what is working, what isn't. Ask yourself, "Are my students getting this?" followed up by, "How do I know?" Now create informal and formal assessments that will confirm their understanding.
Hope this helps.