The lit part of the moon in the dark sky is white, of course. What do you do when teaching on a whiteboard? If I use a blackboard, shading (with white chalk) the part that is lit make sense. However, I am always teaching on a whiteboard and using white paper in class. Therefore, I shade (with dark markers) the part that is lit. I always draw a dotted circle and then fill in the part I can see. So a new moon is just a dotted circle and a full moon is completely filled in (I can see it!). There’s something positively feel-good and reinforcing about marking what you can see rather than trying to shade what you can’t see. What do you think? I have students that argue with me about this every now and then, but I’m stuck in my old habits. I make it very clear at the beginning of class what my convention is. Recently, I’ve had second thoughts. What do you think? What do you do in your classes?