Instructions

  • Turtle is easiest to learn when controlled interactively

  • For an overview of available commands, see the documentation

  • Open a terminal/command prompt and launch Python (by typing 'py', 'python.exe', 'python', or 'python3' depending on your system)

  • Interactive mode should show this prompt: ">>>"

Create a Turtle object called testudo

import turtle
testudo = turtle.Turtle()

Move testudo around to draw a square

testudo.forward(200)
testudo.left(90)
testudo.forward(200)
testudo.left(90)
testudo.forward(200)
testudo.left(90)
testudo.forward(200)
testudo.left(90)

  • Notice how this shape consists of the same steps repeated 4 times

Make this into a function

  • First define a function

  • Note that in interactive mode you have to be careful not to hit enter more than once inside your function definition or python will think your function is finished

def square(t, length):
  for x in range(4):
      t.forward(200)
      t.left(90)

  • Next, you need to call your function, passing in the testudo object and the length of a side

square(testudo, 200)

  • By now your screen might be getting cluttered, so to start again you can break out of the interactive session with CTRL-D or exit()

  • When you restart python interactively, use up/down arrows to scroll through your command history in order to save some typing

Challenge

  1. Write a function called polygon() that takes two parameters, sides and length.

  2. Sides represents the number of sides (3 is a triangle, 4 is a square, etc.)

  3. Length represents the length of a single side

  4. Note that for any polygon the interior angles will add up to 360

  5. This means that a generic polygon function can compute the interior angle by dividing 360 by the number of sides (a square has 4 sides and 360/4 = 90)