We began class with an entry task asking students to ponder: where do trees get their mass from?  Students had some time to think about the question and write or draw pictures describing their ideas.  Selected students or small groups of students were asked to share their ideas publicly on the class white boards (pictures below).  The ideas were labeled as possible hypothesis statements.  Students then had to select the hypothesis they believed to be the most correct and then wrote a conclusive statement explaining their understanding of the science behind the hypothesis statement.

We followed that with a video:

After the video, students received the first draft of their conclusions back for more focused editing.  Slides 3 and 4 of the attached slide deck helped the students focus their scientific writing on clearly articulating the claim, evidence, and reasoning for their revised conclusion.