Drawing moon phases - what’s your opinion?

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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?
 

Answers and Replies

  • #2
Kurdt
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I think the students are just being difficult for the sake of it. You draw the part you can see.
 
  • #3
Borek
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I think on white the picture is counterintuitive and can make the subject more difficult to grasp.
 
  • #4
Kurdt
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I don't think its counterintuitive at all. People mainly grow up with writing on white backgrounds (paper). If anything it is the blackboard that is counterintuitive. Personally I've never thought of either as counterintuitive since the picture depicts what you observe no matter what colour the background is or the ink that the picture is drawn with. You draw the light, not the absence of it. In art when people deliberately draw the 'negative' of an image you can tell the difference since it looks wrong compared to the convention.
 
  • #5
Borek
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IMHO on the white paper you draw shadows which are lack of light. You may draw additional contours to help grasp what is on the picture, but you don't draw the light (unless you are trying to explain how lenses are working :smile:).
 
  • #6
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Why don't you get another color marker, say a red one. Then red can be white and black can be black.
 
  • #7
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If you want to be shading the part you can't see, then for consistency you need to shade the whole damn board :)

Colouring in the bit you can see (as you've been doing) makes more sense to me.
 
  • #8
Alfi
Pretend everything I draw on this board is just a representative interpretation of what you have seen with your own eyes all your life, ok? If you need a refresher look outside tonight.

Then you can draw anything you want. ;)
 
  • #9
LowlyPion
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Why not just outline the visible part omitting the remainder of what is in shadow? A below quarter moon draws as a crescent; a greater than quarter less than a full circle. That's the way they are often drawn in books as outlines.

Wikipedia Junior shows this.

http://upload.wikimedia.org/wikipedia/commons/d/d1/Moon_symbol.ant.png

That just screams waxing moon to me.
 

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