Stealing part of a lesson almost wholesale from the great Sam Shah, I introduced all of the language of graph sketching today in response to my students struggling to describe what was happening in our infection simulation yesterday. Then they colored graphs to immediately figure out the concepts visually. Seeing them struggle to figure out where a function was concave up and down (especially because not a soul had heard those words before) was helpful for me to understand why my students have had problems with this in the past. I don't think I spent enough time in the past just making sure they understood what concavity was in the first place! More coloring tomorrow.