The biggest takeaway from building the unit plan was seeing how everything connects to each other in the big picture of learning. For my unit I had the big goal of having students be able to model something and then analyze it, but the students can't start there. Students have to start with where their knowledge is first and then we have to build up the unit with standards and ideas and learning to reach that final goal. So, my biggest takeaway really was just seeing how you have to take that final goal and figure out the steps in learning (what standards are you using? Where are you using each standard? How does each new learning scaffold to the next learning? How are you building up the cognitive rigor through the unit, and why are you building the cognitive rigor in that way?) to reach that goal.
I think for the next unit plan I create I would start with the big idea and essential questions like I did for this unit plan, but then I might make some tentative, smaller, intermediary ideas that can be used to get to the big idea. One of my struggles with this unit plan was figuring out which standards I wanted/needed for the unit, and I think if I had some of the smaller, intermediary goals of the unit already in my head before going to the standards I would have had an easier time selecting appropriate standards for the unit.
My advice for next semester's students would be to really think about what learning is necessary in your unit to reach your big idea for the unit. Figure out the learning path necessary to reach that end goal, because that path will help you in selecting standards, and understand what data you need to see from students for assessment.