import turtle

screen = turtle.Screen()
screen.title("Snake")
screen.bgcolor("#4A752C")
screen.setup(500, 500)
screen.tracer(0)

pen = turtle.Turtle()
pen.hideturtle()
pen.penup()
pen.shape("square")

for row in range(20):
    for col in range(20):
        x = -200 + col * 20
        y = -200 + row * 20
        if (row + col) % 2 == 0:
            pen.color("#AAD751")
        else:
            pen.color("#A2D149")
        pen.goto(x, y)
        pen.stamp()

snake = [(-40, 0), (-20, 0), (0, 0)]

snake_pen = turtle.Turtle()
snake_pen.hideturtle()
snake_pen.penup()
snake_pen.shape("square")
snake_pen.color("#4673E8")

direction = [20, 0]

def move():
    head = snake[-1]
    new_head = (head[0] + direction[0], head[1] + direction[1])
    snake.append(new_head)
    snake.pop(0)

    snake_pen.clear()
    for part in snake:
        snake_pen.goto(part)
        snake_pen.stamp()

    screen.update()
    screen.ontimer(move, 150)

def go_up():
    direction[0] = 0
    direction[1] = 20

def go_down():
    direction[0] = 0
    direction[1] = -20

def go_left():
    direction[0] = -20
    direction[1] = 0

def go_right():
    direction[0] = 20
    direction[1] = 0

screen.listen()
screen.onkey(go_up,    "Up")
screen.onkey(go_down,  "Down")
screen.onkey(go_left,  "Left")
screen.onkey(go_right, "Right")

move()

screen.mainloop()

_{Project 5 — Step 3 of 5}

⭐ Step 3 — Steer with arrows

➡️ Make the arrow keys change the snake’s direction.

We write four tiny functions — one per arrow — that each change the direction list. Then screen.onkey(fn, "Up") connects each arrow to its function. The screen calls our function whenever the kid presses that arrow.

✏️ What to type

Between the move() definition and the move() call, add:

• go_up, go_down, go_left, go_right — each sets direction to point that way
• screen.listen() (turns on key listening)
• Four screen.onkey(fn, "...") lines connecting each key

Tap 💡 Solution to see the full file.

import turtle

screen = turtle.Screen()
screen.title("Snake")
screen.bgcolor("#4A752C")
screen.setup(500, 500)
screen.tracer(0)

pen = turtle.Turtle()
pen.hideturtle()
pen.penup()
pen.shape("square")

for row in range(20):
    for col in range(20):
        x = -200 + col * 20
        y = -200 + row * 20
        if (row + col) % 2 == 0:
            pen.color("#AAD751")
        else:
            pen.color("#A2D149")
        pen.goto(x, y)
        pen.stamp()

snake = [(-40, 0), (-20, 0), (0, 0)]

snake_pen = turtle.Turtle()
snake_pen.hideturtle()
snake_pen.penup()
snake_pen.shape("square")
snake_pen.color("#4673E8")

direction = [20, 0]

def move():
    head = snake[-1]
    new_head = (head[0] + direction[0], head[1] + direction[1])
    snake.append(new_head)
    snake.pop(0)

    snake_pen.clear()
    for part in snake:
        snake_pen.goto(part)
        snake_pen.stamp()

    screen.update()
    screen.ontimer(move, 150)

# Add 4 tiny functions: go_up, go_down, go_left, go_right.
# Each one sets direction[0] and direction[1] to point that way.

# Then add:
#   screen.listen()
#   screen.onkey(go_up,    "Up")
#   screen.onkey(go_down,  "Down")
#   screen.onkey(go_left,  "Left")
#   screen.onkey(go_right, "Right")

move()

screen.mainloop()

Tap ▶ Run. Click the game window once (so it can hear keys), then press the arrow keys. The snake should turn!

🔍 Tip

We pass go_up to onkey without parentheses. We’re handing the function itself to the screen so it can call it later — not calling it right now.

Next → Step 4

_{⬅ Back to Step 2}