Advanced — Day 1

Moving Snake & Controls

Day Schedule

Online

Time	Activity
10:00	Welcome + Demo Run the full AI snake game; explain what the week looks like
10:20	Pre-Assessment Link provided separately
10:35	Fast Review Variables, libraries, turtle setup — 30–45 min max
11:05	Snake Head + Movement Direction functions, key bindings, game loop, wall collision
11:10	Break
11:20	Breakout Groups Moving snake with arrow keys and wall collision
12:20	Reminders

In-Person

Time	Activity
8:00	Welcome + Demo Run the full AI snake game; explain what the week looks like
8:20	Pre-Assessment Link provided separately
8:35	Fast Review Variables, libraries, turtle setup — 45 min max
9:20	Snake Head + Movement Direction functions, key bindings, game loop, wall collision
9:40	Break
9:50	Breakout Groups Moving snake with arrow keys and wall collision
11:00	Break
11:10	Open Coding Extend or polish Day 1 code; experiment with speed and step size
12:20	Reminders

Learning Objectives

Set up screen, snake head, direction functions, and key bindings
Run a working game loop with movement and wall collision

Project

# INSTRUCTOR — Day 1: Snake — Moving Head & Controls (Advanced)
# -----------------------------------------------
# TEACH: Advanced students have prior Python experience.
# Spend 30–45 min max on a fast review of variables, conditionals, and functions.
# Then go straight into Turtle. The real Day 1 goal is a moving snake with controls.
#
# KEY PATTERN: setheading() + forward() is the entire movement system.
# head.setheading(90) points the snake up. head.forward(20) moves it 20px that way.
# Everything else in snake is built around this two-line pattern.
#
# Headings: 0 = right (east)  90 = up (north)  180 = left (west)  270 = down (south)
#
# DIRECTION GUARD: we block the REVERSE heading, not the current one.
# go_up blocks 270 (DOWN). If heading is already UP and you press UP again, nothing bad
# happens. If heading is DOWN and you press UP, you'd reverse — that's what we block.
#
# CHECK: all four arrow keys work and direction guards prevent reversal.
# COMMON MISTAKE: head drawn with pendown — it trails ink as it moves.
#   Fix: call head.penup() before head.goto(0, 0).

import turtle
import time

screen = turtle.Screen()
screen.title("Snake Game")
screen.bgcolor("black")
screen.setup(width=600, height=600)
screen.tracer(0)   # TEACH: tracer(0) = we call screen.update() manually each frame

head = turtle.Turtle()
head.shape("square")
head.color("white")
head.penup()
head.goto(0, 0)

def go_up():
    if head.heading() != 270:   # 270 = DOWN = the reverse of UP
        head.setheading(90)

def go_down():
    if head.heading() != 90:    # 90 = UP = the reverse of DOWN
        head.setheading(270)

def go_left():
    if head.heading() != 0:     # 0 = RIGHT = the reverse of LEFT
        head.setheading(180)

def go_right():
    if head.heading() != 180:   # 180 = LEFT = the reverse of RIGHT
        head.setheading(0)

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

# TEACH: head runs off screen until Day 2 adds wall collision — that's fine for now.
while True:
    screen.update()
    head.forward(20)
    time.sleep(0.1)

Extra — Draw Border

# INSTRUCTOR — Day 1: Extra Activity: Draw the Border (Advanced)
# -----------------------------------------------
# TEACH: The final snake game has a gold border. Students reproduce it using a for loop.
# This reinforces: turtle setup, goto() to position a starting corner,
# for loop with a fixed number of iterations, forward() and left() to draw a square.
# Answers: start corner (-300, -300), 4 sides, 600 forward, 90 degrees left.

import turtle

halfSize = 300

drawer = turtle.Turtle()
drawer.color("gold")
drawer.width(15)        # TEACH: width() sets line thickness
drawer.speed(0)
drawer.penup()
drawer.goto(-halfSize, -halfSize)   # bottom-left corner
drawer.pendown()

for i in range(4):          # a square has 4 sides
    drawer.forward(halfSize * 2)    # each side is 600px (halfSize * 2)
    drawer.left(90)         # TEACH: left() turns counterclockwise; right() turns clockwise

drawer.hideturtle()

# TEACH: challenge — change border color based on a score variable
score = 0
border_color = "gold"
if score > 5:
    border_color = "cyan"
elif score > 10:
    border_color = "red"
# TEACH: they'd need to redraw the border each time score changes
# (or use a pen turtle that writes on top — hint toward Day 2's score display)

turtle.done()