3.5. Practice Makes Perfect

Turtle Commands

Command	What does it do?
forward( distance )	Move forward a specified distance
backward( distance )	Move backward a specified distance
left(90)	Turns 90 degrees to the left (you can use any angle, not just 90!)
right(90)	Turns 90 degrees to the right
circle( radius )	Draws a circle with the specified radius
goto( x, y )	Move straight to the position with coordinates (x, y). Note: the center is (0, 0)
up()	Stop leaving a trail
down()	Start drawing a trail
color( c )	Set the color to c (https://trinket.io/docs/colors)
for i in range( n ):	Repeat n times

If you don’t remember what these commands do, give them a try below!

import turtle turtle.forward(100) turtle.backward(100) # try out some other commands here!

Let’s take another look at drawing a square. How could we re-write it using a loop?

import turtle turtle.forward(100) turtle.left(90) turtle.forward(100) turtle.left(90) turtle.forward(100) turtle.left(90) turtle.forward(100) turtle.left(90)

Let’s use what we know about loops to draw a dashed line across the entire box!

The code below draws two dashes. See if you can modify it to use a loop!

import turtle # draw the first dash turtle.forward(10) # pick the pen up to leave white space between dashes turtle.penup() turtle.forward(10) # put the pen down and draw the second dash turtle.pendown() turtle.forward(10) turtle.penup() turtle.forward(10)

Why stop with squares? Shapes with any number of sides can be drawn using a loop!

Start with your code that draws a square. Then, change the number of times the loop repeats and the angle that you turn each time to see if you can draw these shapes.

import turtle

Try converting you dashed line into a row of circles! Let’s draw 20 circles, each with a radius of 10.

import turtle

Try drawing a row of squares!

For this problem, try using two loops! One to draw each square (same as in the first problem on this page), and another to draw the square multiple times

import turtle

Try drawing a plus sign using a loop!

If you’re not sure how to do it with a loop, try writing it out line by line first. Once you’ve got it drawing a plus sign, see if you can put any repeated code in a loop!

import turtle

Now try modifying your code from the plus sign into an asterisk!

Hint: you’ll need to change the number of repetitions and the angle that you’re turning each time

import turtle

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