Students did some problems where the energy of the system is changing. The other physics teacher and I skipped having students define their system due to time constraints, but some of the mistakes I’m seeing could be fixed by having students take that step, so I will be going back to the full LOL diagrams next year.
Students did some problems calculating theoretical yield for chemical reactions. When we first started balancing chemical equations, I required students to sketch a diagram of the atoms involved to emphasize that the atoms are just being rearranged. Today, I left it up to students whether they wanted to include the sketch or not, and it drove home for me how important concrete, conceptual tools are when nearly every student still drew the diagrams.