🎯 Worksheet 1: Click the Circle

Your first Python game! Today we’re making a simple clicking game. In Scratch, you’d drag blocks. In Python, you’ll type the code. Same ideas, new way of writing them!

📝 IMPORTANT: Type, Don’t Copy!

Type every line of code yourself - don’t copy and paste! Making mistakes and fixing them is how you learn. Your fingers need to learn where the symbols are!

After each step:

• Run your code to see what happens
• Change some numbers to see what they do
• Break it and fix it - that’s how you learn!

Part 1: Make a Window

Let’s start super simple. Type this code exactly as shown:

def setup():
    size(800, 600)

def draw():
    background(173, 216, 230)

run_sketch()

Run it! You should see a light blue window appear.

What’s happening?

• setup() runs once when your program starts (like “when green flag clicked”)
• draw() runs over and over, 60 times per second (like a “forever” loop)
• size(800, 600) makes a window 800 pixels wide, 600 pixels tall
• The numbers in background() are RGB colors (Red, Green, Blue) from 0-255

🔬 Experiment Time!

Before moving on, try changing:

• The window size to size(400, 400) - what happens?
• The background numbers to background(255, 0, 0) - what color is that?
• What happens if you delete the background() line entirely?

Change it back when you’re done experimenting!

Part 2: Add a Circle

Now let’s put a circle in our window. Add these lines to your draw() function:

def draw():
    background(173, 216, 230)

    # Draw a red circle
    fill(255, 100, 100)
    circle(400, 300, 80)

Run it! You should see a light red circle in the middle of your window.

What’s new?

• fill() sets the color for shapes (like choosing sprite colors)
• circle(x, y, size) draws a circle at position x, y
• # makes a comment - Python ignores these, they’re just for humans

🔬 Experiment Time!

• Change the circle position: try circle(100, 100, 80)
• Make it huge: circle(400, 300, 300)
• Try fill(0, 255, 0) - what color is that?
• What happens if you add another circle() line with different numbers?

Part 3: Make It Clickable

Time to detect clicks! Add this new function at the bottom (before run_sketch()):

def mouse_pressed():
    print("You clicked!")

Run it and click anywhere! Look at the console/output area - you should see “You clicked!” appear each time you click.

🔬 Experiment Time!

• Change the message to print your name
• Try printing mouse_x and mouse_y to see where you clicked
• What happens if you put print("Hello") in the draw() function instead?

Part 4: Add a Score

Let’s count the clicks! Add a score variable at the very top of your program:

score = 0

def setup():
    size(800, 600)

def draw():
    background(173, 216, 230)

    # Draw a red circle
    fill(255, 100, 100)
    circle(400, 300, 80)

    # Show the score
    fill(0)  # Black text
    text_size(32)
    text(f"Score: {score}", 20, 40)

def mouse_pressed():
    global score
    score = score + 1
    print(f"Score: {score}")

run_sketch()

Run it! Click anywhere and watch the score go up!

Important: The global keyword

• When you want to change a variable inside a function, you need global
• This tells Python “I want to change the score variable from outside this function”
• In Scratch, variables just work everywhere - in Python, we need to be specific

🔬 Experiment Time!

• Try removing the word global - what error do you get?
• Change score = score + 1 to score = score + 10 for mega points!
• Add another text line showing “Click anywhere!” as instructions
• Change the text size and position

Part 5: Only Count Circle Clicks

Right now clicking anywhere adds to the score. Let’s fix that! We need to check if the click is inside the circle.

Update your mouse_pressed() function:

def mouse_pressed():
    global score

    # How far is the mouse from the circle center?
    distance = dist(mouse_x, mouse_y, 400, 300)

    # Is it inside the circle? (circle radius is 40)
    if distance < 40:
        score = score + 1
        print("Hit!")

Run it! Now only clicking the circle increases the score!

What’s happening?

• dist() measures distance between two points (like sensing blocks in Scratch)
• mouse_x and mouse_y tell you where the mouse is
• if checks a condition - just like “if-then” blocks in Scratch
• The circle’s radius is half its size (80 ÷ 2 = 40)

🔬 Experiment Time!

• Add an else: block to print “Missed!” when you click outside
• Try printing the exact distance value to see how it changes
• What happens if you change < 40 to < 100? Why?

Part 6: Make the Circle Move

Let’s make it a real game! First, add the random library and circle position variables at the top:

import random

score = 0
circle_x = 400
circle_y = 300

Now update your code to use these variables:

def draw():
    background(173, 216, 230)

    # Draw circle at its position
    fill(255, 100, 100)
    circle(circle_x, circle_y, 80)

    # Show the score
    fill(0)
    text_size(32)
    text(f"Score: {score}", 20, 40)

def mouse_pressed():
    global score, circle_x, circle_y

    # Check if clicked on circle
    distance = dist(mouse_x, mouse_y, circle_x, circle_y)

    if distance < 40:
        score = score + 1
        # Move circle to random position
        circle_x = random.randint(50, 750)
        circle_y = random.randint(50, 550)

Run it! Click the circle and it jumps to a new spot!

What’s new?

• import random lets us use random numbers (like pick random block)
• random.randint(50, 750) picks a random number between 50 and 750
• We keep the circle away from edges (50 pixels from each side)

🔬 Experiment Time!

• Change the random range to random.randint(0, 800) - what happens?
• Make the circle start at a random position (hint: call the random function in setup())
• Try adding print(f"Circle at: {circle_x}, {circle_y}") to see where it goes

🎉 Complete Game!

You’ve made your first Python game! Here’s the complete code:

import random

score = 0
circle_x = 400
circle_y = 300

def setup():
    size(800, 600)

def draw():
    background(173, 216, 230)

    # Draw circle
    fill(255, 100, 100)
    circle(circle_x, circle_y, 80)

    # Show score
    fill(0)
    text_size(32)
    text(f"Score: {score}", 20, 40)

    # Instructions
    text_size(16)
    text("Click the circle!", 20, 70)

def mouse_pressed():
    global score, circle_x, circle_y

    distance = dist(mouse_x, mouse_y, circle_x, circle_y)

    if distance < 40:
        score = score + 1
        circle_x = random.randint(50, 750)
        circle_y = random.randint(50, 550)

run_sketch()

🚀 Make It Your Own!

Try these changes - type them yourself and see what happens!

Easy Changes

Color picker tip: Use rgbcolorpicker.com to pick any color! Copy the R, G, and B values (in that order) into your fill() or background() commands.

1 - Change circle color - Make your circle any color you want using RGB values

2 - Change background color - Give your game a different background

3 - Make it harder - Shrink the circle so it’s harder to click

4 - Change window size - Make your game area bigger or smaller

5 - Personalize the score - Add your name to the score display

Challenges

if score >= 10:
    text_size(48)
    text("YOU WIN!", 300, 300)

circle_red = 255
circle_green = 100
circle_blue = 100

circle_red = random.randint(0, 255)
circle_green = random.randint(0, 255)
circle_blue = random.randint(0, 255)

def draw():
    # ... your existing draw code ...

    global score
    distance = dist(mouse_x, mouse_y, circle_x, circle_y)
    if distance < 40:
        score = score + 1
        # Move circle immediately

🤔 Think About It

How is this similar to Scratch? How is it different?

• Similar: We have sprites (circles), sensing (mouse clicks), variables (score), and forever loops (draw function)
• Different: We type instead of drag, we need exact spelling, we use indentation to show what’s inside what