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():
    # New head = old head + direction
    head = snake[-1]
    new_head = (head[0] + direction[0], head[1] + direction[1])
    snake.append(new_head)
    snake.pop(0)

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

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

move()

screen.mainloop()

_{Project 5 — Step 2 of 5}

⭐ Step 2 — Make it move

➡️ Make the snake slide forward by itself.

The trick is small but clever:

1. Add a new piece at the front (head) of the snake
2. Remove the piece at the back (tail)
3. Result: the snake slid forward one step

Do that over and over every 150 ms using screen.ontimer (like the rocket animation in Project 3, but faster).

✏️ What to type

After the snake setup (and before screen.mainloop()), add:

• A direction list with [20, 0] (means 20 right, 0 up)
• A move() function that adds a new head, drops the tail, redraws, and schedules itself with ontimer
• A single move() call to start it going

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")

# 1. Add: direction = [20, 0]

# 2. Add a move() function that:
#    - calculates new_head from snake[-1] + direction
#    - appends new_head, pops snake[0] (slide forward)
#    - clears snake_pen and redraws every part
#    - calls screen.update() and screen.ontimer(move, 150)

# 3. Call move() once at the bottom (before screen.mainloop) to start it.

screen.update()
screen.mainloop()

Tap ▶ Run. The snake should slide to the right by itself. It’ll fly off the edge of the board — we’ll fix that in Step 5.

🔍 Tip

snake[-1] is the last item in the list. snake.append(x) adds to the end. snake.pop(0) removes the first. Together, that’s a slide forward.

Next → Step 3

_{⬅ Back to Step 1}