Clock Face

By the end of this lab you'll be able to:

• Draw a clock face with tick marks and hour numbers
• Convert hours, minutes, and seconds into angles for clock hands
• Use setheading() to point each hand at the correct angle

A complete analog clock face — outer ring with 60 tick marks, 12 numbered hours, and three hands (hour, minute, second) drawn at computed angles.

Welcome to the Clock Face!

An analog clock is a math problem: convert time into angles! The minute hand moves 6° per minute, the hour hand moves 0.5° per minute. Let's compute it and draw it!

How It Works

Angles for hands: second_angle = 90 - seconds * 6, minute_angle = 90 - minutes * 6 - seconds * 0.1, hour_angle = 90 - hours * 30 - minutes * 0.5. A draw_hand(angle, length, width) function draws a hand at the given angle.

Sample Code

import turtle
import math
monty = turtle.Turtle()
monty.speed(0)
monty.hideturtle()

def draw_tick(angle, length, width):
    monty.penup()
    r = 130
    rad = math.radians(angle)
    monty.goto(r * math.cos(rad), r * math.sin(rad))
    monty.setheading(angle + 180)
    monty.pendown()
    monty.pensize(width)
    monty.forward(length)

for i in range(60):
    angle = 90 - i * 6
    if i % 5 == 0:
        draw_tick(angle, 15, 3)
    else:
        draw_tick(angle, 8, 1)

monty.pencolor('black')
for h in range(1, 13):
    angle = 90 - h * 30
    rad = math.radians(angle)
    monty.penup()
    monty.goto(100 * math.cos(rad) - 8, 100 * math.sin(rad) - 8)
    monty.write(str(h), font=('Arial', 9, 'bold'))

def draw_hand(angle, length, color, width):
    rad = math.radians(angle)
    monty.penup()
    monty.goto(0, 0)
    monty.pendown()
    monty.pencolor(color)
    monty.pensize(width)
    monty.goto(length * math.cos(rad), length * math.sin(rad))

hours, minutes, seconds = 10, 10, 30
sec_angle = 90 - seconds * 6
min_angle = 90 - minutes * 6 - seconds * 0.1
hr_angle = 90 - hours * 30 - minutes * 0.5

draw_hand(hr_angle, 60, 'black', 4)
draw_hand(min_angle, 90, 'black', 3)
draw_hand(sec_angle, 110, 'red', 1)
monty.penup(); monty.goto(0, 0); monty.dot(8, 'black')

What Do You Think Will Happen?

The code sets hours=10, minutes=10, seconds=30. Before running, look at an analog clock and imagine where the hands should point. Make your prediction — then click Run!

Try It Now

▶ Run ↻ Reset

A clock showing 10:10:30 — the hour hand between 10 and 11 (already past the 10), minute hand at 2 (10 minutes), second hand at 3 (30 seconds). Were you right?

How It Works

Clock angles: - Each second = 6° clockwise = −6° in turtle angle - Each minute = 6° clockwise; the second also moves the minute hand slightly (0.1° per second) - Each hour = 30° clockwise; the minute also moves the hour hand (0.5° per minute)

Explanation Table

Line	What it does
sec_angle = 90 - seconds * 6	0s = 12 o'clock = 90°, each second = −6°
min_angle = 90 - minutes*6 - seconds*0.1	Minute hand moves smoothly
hr_angle = 90 - hours*30 - minutes*0.5	Hour hand moves between hours
i % 5 == 0	Every 5th tick is a long hour tick

Learning Check

Your Turn — Change the Time

Change to hours=3, minutes=45, seconds=0. Before running, visualize where each hand will point. Then run to verify!

▶ Run ↻ Reset

3:45:00 — the minute hand at 9, the hour hand 3/4 of the way between 3 and 4 (because 45 minutes = 3/4 of the way to the next hour).

Experiments

1. Display your current time. Use Python's datetime module: import datetime; now = datetime.datetime.now() then hours = now.hour % 12; minutes = now.minute; seconds = now.second. You'll know it worked when the clock shows the actual current time.

2. Add a colored clock face. Draw a filled circle in a light color behind the tick marks. You'll know it worked when the clock has a colored background.

3. Make the hands colored. Use different colors for hour, minute, and second hands. You'll know it worked when each hand is visually distinct.

4. Add Roman numerals. Replace the number labels with Roman numerals. You'll know it worked when I, II, III... appear around the clock.

Tick Tock!

You built a working analog clock face from scratch using angle math! The same angle = 90 - n * step formula works for any clock-like display. Up next: Spirograph Drawer — interactive spirograph with changing parameters.