Thank you Dr. Wicklin for your post (this one and all of the others). I would like to use your example here to give students in my introductory statistics class a visualization of slopes to help them understand the concept of probability density. My stats course is a general education course but students in the class are almost all majors in psychology and sociology who will need a somewhat developed understanding of probability density before going on to their advanced stats courses. I think the example you provide here is an excellent introduction for my students. If you have any additional examples or thoughts about how to teach probability density to non-math majors, I would love to hear from you.