One of the many problems the kids worked on today is below. What I enjoyed most about this problem is that two of my students worked right through frustration and obtained the correct solution.
I jumped in while the students were struggling to model how I would try and find the possible boundaries for the value of the sum.
It was satisfying to work through what the students had done and discovering their work was correct. I was so focused on the work I totally missed the students' guerrilla addition to my meeting announcement. "Be there... or be taken to the second power!"