teacher_notes.md

Week 8 – Pattern Maker (Loops + Turtle)

Objectives

• Use nested loops to create complex patterns
• Understand rotation to create spiral/circular patterns
• Learn the relationship between sides and angles (360/sides)
• Introduce while loops as an alternative to for loops
• Apply mathematical thinking to visual patterns

Concept explanation (kid-friendly)

• Patterns are made by repeating shapes while rotating
• We can use math to figure out angles: 360 ÷ number of sides
• Nested loops mean "a loop inside a loop" - outer loop rotates, inner loop draws
• While loops repeat "while" a condition is true (different from "repeat N times")

New Python concept: while loops

• for loop: "Do this exactly N times" → for i in range(10):
• while loop: "Do this while condition is true" → while score < 10:
• Example: Game keeps going WHILE player has lives
• Example: Pattern continues WHILE rotation < 360 degrees

Connection to previous weeks

• Week 7: We drew shapes with functions
• Week 5: We used for loops for training rounds
• Week 8: We combine loops + rotation to make patterns
• Scratch equivalent: "Repeat until" (while) vs "Repeat 10" (for)

Lesson flow (60–75 min)

1) Warm-up (5–10 min)

• Review: "How do we draw a square?" (4 sides, 90-degree turns)
• Question: "What angle do we need for a hexagon?" (360÷6 = 60 degrees)
• Quick demo: Run week08.py and observe the patterns

2) New concept (10–15 min)

Part A: Angle mathematics (5 min) Draw on board:

• Triangle: 3 sides → turn 360÷3 = 120 degrees
• Square: 4 sides → turn 360÷4 = 90 degrees
• Pentagon: 5 sides → turn 360÷5 = 72 degrees
• Hexagon: 6 sides → turn 360÷6 = 60 degrees

Part B: While loops (5 min) Show comparison:

# For loop: Exact count
for i in range(5):
    print("Round", i+1)

# While loop: Until condition
rounds = 0
while rounds < 5:
    print("Round", rounds+1)
    rounds = rounds + 1

When to use each:

• Use for when you know how many times
• Use while when you repeat until something happens

Part C: Nested loops for patterns (5 min)

for _ in range(6):      # Outer: repeat 6 times
    for _ in range(4):  # Inner: draw a square
        t.forward(60)
        t.right(90)
    t.right(60)         # Rotate before next square

3) Guided build (20–25 min)

Part A: Simple polygon (10 min)

sides = 6               # Try changing this!
step = 80
turn = 360 / sides      # Math calculates the angle

for _ in range(sides):
    t.forward(step)
    t.right(turn)

• Experiment together: Change sides to 3, 4, 5, 8
• Observe: The angle changes automatically
• Question: "What happens with sides = 360?" (Almost a circle!)

Part B: Pattern with rotation (10 min)

for _ in range(18):     # Outer loop: repeat pattern 18 times
    for _ in range(4):  # Inner loop: draw one square
        t.forward(60)
        t.right(90)
    t.right(20)         # Rotate 20 degrees before next square

• Draw diagram: Show how each square rotates
• Math: 18 squares × 20 degrees = 360 degrees (full circle)
• Ask: "What if we used 10 degrees?" (Need 36 squares for full circle)

Part C: While loop alternative (5 min) Show how we could use while instead:

rotation = 0
while rotation < 360:
    for _ in range(4):
        t.forward(60)
        t.right(90)
    t.right(20)
    rotation = rotation + 20

Same result, different approach!

4) Independent challenge (15–20 min)

Task A: Run and observe

• Run the program
• Identify the two patterns
• Count how many shapes in the circular pattern

Task B: Modifications (from student_tasks.md)

• Change sides to 8 and observe
• Change the outer loop range to 12 (instead of 18)
• Change rotation angle from 20 to 10
• Change square size from 60 to 40

Task C: Creative challenges

• Create a pattern with triangles instead of squares
• Make a pattern that uses both squares and hexagons
• Create a spiral pattern using while loop with increasing size
• Try making a "flower" pattern (circles arranged in circle)

Challenge extension:

# Spiral with increasing size
size = 10
while size < 200:
    t.forward(size)
    t.right(90)
    size = size + 5

5) Wrap-up (5 min)

Students explain:

• "How do we calculate the turn angle for any shape?"
• "What's the difference between for and while loops?"
• "What does the outer loop do vs the inner loop?"
• "How would you create a 10-pointed star pattern?"

Common errors to demo on purpose

1. Wrong angle calculation

   sides = 5
   turn = 360 * sides  # Wrong! Should be 360 / sides

   • Shows: Weird shape that doesn't close
   • Fix: Use division, not multiplication

2. Infinite while loop

   count = 0
   while count < 10:
       t.forward(50)
       # Forgot to increment count!

   • Shows: Loop never ends, program freezes
   • Fix: Add count = count + 1 inside loop

3. Nested loop confusion

   for _ in range(18):
       t.forward(60)      # Moved out of inner loop
       for _ in range(4):
           t.right(90)

   • Shows: Broken pattern
   • Fix: Keep shape-drawing code in inner loop

4. Speed too slow

   t.speed(1)  # Very slow
   # With complex patterns

   • Shows: Takes forever to complete
   • Fix: Use t.speed(0) for instant drawing

Success criteria

• Student can explain the 360/sides formula
• Student can modify pattern parameters and predict results
• Student can explain difference between for and while loops
• Student can identify outer vs inner loops in nested structure
• Student creates at least one custom pattern

Differentiation

For students who need support:

• Start with just the simple polygon (first part)
• Provide pre-calculated angles (don't worry about formula yet)
• Use only for loops (skip while loops initially)
• Limit to 2 patterns total

For advanced students:

• Create 3+ different patterns in one program
• Experiment with color changes in loops (t.color())
• Create patterns with 3 nested loops
• Use while loop with user input to control pattern
• Research and implement Spirograph-style patterns

Materials needed

• Thonny IDE
• week08.py file
• Calculator (for angle calculations)
• Optional: Compass and protractor for visual demo
• Optional: Printout of angle formula table

Key vocabulary

• Nested loop: Loop inside another loop
• Outer loop: The loop that contains another loop
• Inner loop: The loop inside another loop
• Rotation: Turning by an angle
• While loop: Loop that continues while condition is true
• Iteration: One pass through a loop

Connection to math curriculum

• Angles and degrees (360° in full rotation)
• Division for equal distribution
• Multiplication for counting rotations
• Geometry: Regular polygons and their properties

Homework/practice

• Create a pattern using triangles (3 sides, 120° turns)
• Make a pattern that uses exactly 10 shapes in a circle
• Draw a spiral that grows outward
• Use a while loop to draw shapes until they reach screen edge