## A2-13: ELLIPSE DRAWING BOARD

• ID Code: A2-13
• Purpose: Demonstrate one method of drawing ellipses
• Description: The ends of a string loop are hooked around two pegs on the board and kept tight by the chalk holder. Moving the string around one complete turn produces an ellipse. This procedure creates the locus of points where R1 + R2 = Constant, the equation for an ellipse. Changing the peg position changes the eccentricity of the ellipse.

Consider inviting students to make predictions about how the shape of the ellipse will change in response to changing the foci in different ways. This can be related to a variety of mathematical and astronomical phenomena.

• Availability: Available
• Loc codes: FS2
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