Write a program that prints we like Python's turtles! 1000 times.

for x in range(1000):
    print("We like Python's turtles!")
Copy

Write a program that uses a for loop to print

One of the months of the year is January
One of the months of the year is February ...

months = ["January", "February", "March", "April", "May", "June", "July", \
    "August", "September", "October", "November", "December"]

for month in months:
    print("One of the months of the year is " + month + ".")
Copy

Assume you have the assignment xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]

Write a loop that prints each of the numbers on a new line.

xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
for x in xs:
    print(x)
Copy

Write a loop that prints each number and its square on a new line.

xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
for x in xs:
   print(str(x) + " squared is " + str(x**2) + ".")
Copy

Write a loop that adds all the numbers from the list into a variable called total. You should set the total variable to have the value 0 before you start adding them up, and print the value in total after the loop has completed.

xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
total = 0
for x in xs:
    total = total + x
print(total)
Copy

Print the product of all the numbers in the list.

xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
total = 1
for x in xs:
    total = total * x
print(total)
Copy

Use for loops to make a turtle draw these regular polygons (regular means all sides the same lengths, all angles the same):

An equilateral triangle

def draw_regular(name, sides, length):
    """ Takes a turtle as name, an integer as sides, and a number as length.
    Causes the turtle to draw a regular polygon with that number of sides, 
    in which each side is of length 'length'."""

    # Draws a side, then turns, for however many sides we need.
    for x in range(sides):
        name.forward(length)
        name.left(360 / sides)

import turtle               # Lets us work with turtles
wn = turtle.Screen()        # Gives us a screen to work on
tess = turtle.Turtle()      # Gives us a turtle on that screen

draw_regular(tess, 3, 50)   # The line that chooses what to draw

wn.mainloop()               # Holds the screen open till the user closes it.
Copy

Because the program above works by calling a function set up to draw a regular polygon with any given number of sides, we can draw different polygons simply by tweaking the second argument in line 15.

A square

Simply change line 15 to draw_regular(tess, 4, 50).

A hexagon

draw_regular(tess, 6, 50)

An octagon

draw_regular(tess, 8, 50)

A drunk pirate makes a random turn and then takes 100 steps forward, makes another random turn, takes another 100 steps, turns another random amount, etc. A social science student records the angle of each turn before the next 100 steps are taken. Her experimental data is [160, -43, 270, -97, -43, 200, -940, 17, -86]. (Positive angles are counter-clockwise.) Use a turtle to draw the path taken by our drunk friend.*

import turtle
wn = turtle.Screen()
pirate = turtle.Turtle()

turns = [160, -43, 270, -97, -43, 200, -940, 17, -86]

for turn in turns:
    pirate.left(turn)
    pirate.forward(100)

wn.mainloop()
Copy

Enhance your program above to also tell us what the drunk pirate’s heading is after he has finished stumbling around. (Assume he begins at heading 0).

We can do this by adding a heading variable, and then updating it every time we turn the pirate. And, while we're at it, we might as well have some comments in the code.

# Make a simulated pirate and a place for him to stumble around.
import turtle
wn = turtle.Screen()
pirate = turtle.Turtle()

# The raw data about how he stumbled.
turns = [160, -43, 270, -97, -43, 200, -940, 17, -86]

# This variable will keep track of our pirate's heading
heading = 0

# Simulate the actual stumbling around.
for turn in turns:
    # The pirate turns.
    pirate.left(turn)
    # We update which way he's facing.
    heading = heading + 1
    # He walks a suspiciously consistent number of steps in a straight line.
    pirate.forward(100)

# Keep the screen open till the user closes it.
wn.mainloop()
Copy

Write a program to draw a shape like this:

# Set up a turtle on a screen.
import turtle
wn = turtle.Screen()
tess = turtle.Turtle()

# Customize speed and pen thickness.
tess.speed(3)
tess.pensize(3)

# Draw the actual shape
for x in range(5):
    tess.forward(200)
    tess.right(144)

# Make the turtle hide so just the shape displays.
tess.hideturtle()

# Hold the window open till the user closes it.
wn.mainloop()
Copy

Write a program to draw a face of a clock that looks something like this:

# Set up screen, turtle, and light green background.
import turtle
wn = turtle.Screen()
wn.bgcolor("lightgreen")
tess = turtle.Turtle()
tess.color("blue")
tess.shape("turtle")
tess.pensize(2)

# The turtle will need to make twelve 'hands' of 
# the clock, turning thirty degrees each time.
for x in range(12):
    tess.left(30)
    tess.penup()
    tess.forward(70)
    tess.pendown()
    tess.forward(7)
    tess.penup()
    tess.forward(13)
    tess.stamp()
    tess.backward(90)

# Hold the screen open till the user closes it.
wn.mainloop()
Copy

This page is released under the GNU Free Documentation License, any version 1.3 or later produced by the Free Software Foundation. I am grateful to the authors of the original textbook for releasing it that way: Peter Wentworth, Jeffrey Elkner, Allen B. Downey, and Chris Meyers.