Explore the Geogebra file shared here. What high school mathematics topics would be unchanged with axes which met at something other than 90 degrees? Which would be changed but would just take time for us to adjust to them? Which things would be mathematically different?  In your groups, brainstorm topics that you think would need to be examined. Be prepared to share out from your group to the whole class in 5 minutes. Keep in mind you do not need to have any thoughts about the behaviors of these topics, just which topics will need to be explored. After each group shares out their list of topics to be explored, and we record them on the board, each group should select which topic they are going to explore first, with each group starting with a different topic.