Saturday, February 11, 2012

Flowcharts and Scratch

The learners could not wait to start experimenting in Scratch when we were doing flowcharts and algorithms.  To show how the flowcharts relate to the programming we created concrete algorithms and flowcharts to draw a square, an equilateral triangle, pentagon and a hexagon and then programmed this in Scratch.

They knew what the angles were supposed to be for the square and triangle, but they had to measure the angles of the regular pentagon and hexagon.  To draw these shapes in MSWord, you use insert shapes and choose the shape.  Then hold down shift while you draw the shape to keep the sides the same length and angles the same size.

To show what the sum of the interior angles is, you can divide the shapes into triangles.  Since the sum of the angles of a triangle is 180 degrees, the sum of the angles in a hexagon is 4 x 180 degrees = 720 degrees since there are 4 triangles inside the hexagon.
Since all 6 angles of the hexagon are the same size, each angle must be 720/6 = 120 degrees.

When the sprite turns, we use 60 degrees (the supplement of 120 degrees)
If you repeat this method for other regular polygons you will find the angle to turn is always 360/(number of sides)
The flowchart could look as follows:

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