4.5. Practice Makes Perfect

Here’s a reminder of the commands we learned last week:

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

And here are the new commands we’ll be learning this week!

Command	What does it do?
begin_fill()	Starts filling in drawn shapes
end_fill()	Stops filling in drawn shapes
speed(number 0-10)	Determines how quickly the turtle will move through commands
def function_name():	Creates and defines a new function
function_name()	Calls a function

First, let’s do a quick review of loops by drawing a square using a loop. Then, we can use that code to check out what these new commands do!

import turtle

Let’s combine what we know about loops with the square function we wrote in the last exercise to draw a row of squares.

import turtle

Try modifying your code from the previous exercise to draw a row of triangles instead. Feel free to add color or fill in the triangles!

import turtle

Let’s take what we know about loops and functions to draw a starry night sky

To draw the star, you’ll need to repeat the following actions 5 times:

• move forward 50 pixels

• turn left 144 degrees

import turtle def star(): # put the commands to draw a star here # once you can draw one star, try moving around and adding more to the sky! star()

How can we use what we know to draw a forest of pine trees?

• How might you draw a forest? Draw a bunch of pine trees!

• How might you draw a pine tree? Draw a stack of triangles!

• How might you draw a stack of triangles? Draw individual triangles offset in a loop!

Follow these steps if you get stuck:

1. Teach your turtle how to draw a triangle() using a for loop

2. Teach your turtle how to draw a tree() by calling triangle() inside of a loop

3. Teach your turtle how to draw a forest() by calling tree() inside of a loop

4. Call your forest() function, and watch the magic happen!

import turtle # write a function to draw a triangle # write a function to draw a tree that calls your triangle function # write a function that draws a forest by calling your tree function

Use the starter code below to draw a row of triangles!

import turtle ##################### define your functions here ###################### def up_triangle(): turtle.color("green") # try changing the colors! turtle.down() turtle.begin_fill() for i in range(3): # teach your turtle how to draw a right-side-up triangle! turtle.end_fill() turtle.up() def down_triangle(): turtle.color("red") # try changing the colors! turtle.down() turtle.begin_fill() # hint: turn 60 before you start looping to make it upside down! for i in range(3): # teach your turtle how to draw an upside-down triangle! # hint: turn 60 back the other way to reset the turtle on track! turtle.end_fill() turtle.up() ############################ main code ############################ turtle.penup() turtle.setposition(-200, 0) for i in range(6): # tell the turtle to draw a right side up triangles then move forward # tell the turtle to draw an upside-down triangle then move forward

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