Lesson 5 reading

The lesson gave you the skeleton: a window, a function of your own, and a square gliding across the screen. This reading is the paint and wheels — the turtle functions that make things look good. Every one of them is just another function call, the shape you already know: a name, parentheses, maybe an input.

Make it look like a turtle

t.shape("turtle")

The arrow becomes an actual little turtle. Small thing, instant charm.

Speed

t.speed(1)   # slowest
t.speed(6)   # normal
t.speed(0)   # FASTEST — zero is special

1 is a crawl and 10 is fast, but 0 is a special value meaning no animation at all — the drawing just appears. Use t.speed(0) when a drawing has lots of lines (you'll want it for the homework spiral).

Pen thickness and color

t.pensize(5)
t.pencolor("red")

Lines come out thick and red until you change them again. Colors are strings — "red", "blue", "green", "orange", "purple", "hotpink" and dozens more all work by name.

The window background belongs to the screen, not the turtle — so that function lives on screen:

screen = turtle.Screen()
screen.bgcolor("black")

Black background, "cyan" pen, t.speed(0) — instant neon.

Lifting the pen

The turtle draws because its pen is down. You can lift it, move without drawing, and put it back down:

t.penup()
t.forward(100)   # moves, no line
t.pendown()
t.forward(100)   # draws again

This is how you draw two shapes with a gap between them — and it's exactly what the animation loop did every frame: pen down to draw the square, pen up to walk to the next spot without leaving a smear.

Jumping to a spot: goto and the map of the window

t.goto(100, 50)

The turtle walks straight to the point (100, 50). The window is a coordinate plane, exactly like math class: (0, 0) is the center of the window, x grows to the right, y grows upward, negative numbers go the other way.

                 (0, 200)
                    |
(-200, 0) ----- (0, 0) ----- (200, 0)
                    |
                (0, -200)

goto draws a line on the way there like any other move — combine it with penup to teleport:

t.penup()
t.goto(-100, -100)
t.pendown()

That pattern — up, goto, down — is how you place shapes wherever you want. You'll use it constantly.

Circles and dots

t.circle(50)     # circle with radius 50, drawn from the bottom
t.dot(20)        # filled dot, 20 across, right where the turtle stands

A circle for a face, two dots for eyes — you can already see where this goes.

Title

One for the screen, because every game needs a name in the title bar:

screen.title("Turtle Hero")

Try it

Same rules as always: predict first, then run. For each one, say out loud what the window will look like before you press Run — where the turtle starts, what color, what gets drawn.

import turtle

t = turtle.Turtle()
t.shape("turtle")
t.pencolor("blue")
t.pensize(3)

t.circle(50)

turtle.done()

import turtle

t = turtle.Turtle()
t.speed(0)

t.penup()
t.goto(-150, 0)
t.pendown()
t.forward(300)

turtle.done()

import turtle

t = turtle.Turtle()
screen = turtle.Screen()
screen.bgcolor("black")
t.pencolor("cyan")

for i in range(4):
    t.forward(100)
    t.left(90)

t.penup()
t.goto(50, 50)
t.dot(20)

turtle.done()

One habit worth keeping: when a drawing surprises you, it's the turtle's position or heading you've lost track of. Slow it down — t.speed(1) — and watch it move. That's "watch the numbers change" from Lesson 3, in picture form.