Assignment task: Apply the idea of clinal variation to the next two questions:
1. Picture our class in an actual classroom. I ask you all to line up around the edge of the room in order of height. When you are lined up I ask you where we should draw the line between the short people and the tall people. Where do we draw it? Can we do it? Why or why not? (It is NOT because the ideas of short and tall are subjective.)
2. We are back in the classroom. I ask you to line up again, this time in order of skin color, from darkest to lightest. I ask where we should draw the line between dark-skinned students and light-skinned students. Where do we draw it? Why is it impossible to decide where to draw the line? (Again, it is NOT because the idea of skin-color is subjective.)