Python for Kids: Build a Number Guessing Game (Step by Step)

"I'm thinking of a number between 1 and 100…" — the guessing game is the perfect first Python project. In about 25 lines of code you will use the most important ideas in programming: variables, input, conditions, loops and random numbers.

By the end, your game will:

• pick a secret number,
• tell the player "too high" or "too low" after each guess,
• count the guesses,
• cope with mistakes (like typing a word instead of a number),
• ask "Play again?".

What you need: Python 3. Download it free from python.org, or install Thonny (thonny.org), a beginner-friendly editor that comes with Python built in. On a Chromebook or school computer, you can use a free online Python editor such as Replit or Trinket.

Step 1: Say hello

Create a new file called guess.py and type:

print("Welcome to the Number Guessing Game!")
print("I'm thinking of a number between 1 and 100.")

Run it (in Thonny, click the green Run button or press F5). You will see the two messages.

print() shows text on the screen. Text inside quotes is called a string.

Step 2: Pick a secret number

Python can choose random numbers using its built-in random module.

import random

secret = random.randint(1, 100)

print("Welcome to the Number Guessing Game!")
print("I'm thinking of a number between 1 and 100.")

• import random loads Python's random-number tools.
• random.randint(1, 100) picks a whole number from 1 to 100 — and both 1 and 100 can be chosen.
• secret = … stores that number in a variable called secret. A variable is a named box that holds a value.

Step 3: Ask for a guess

guess = int(input("Your guess: "))

• input() waits for the player to type something and press Enter. It always gives back text.
• int() turns that text into a whole number, so we can compare it with secret.

Step 4: Give hints with if, elif and else

if guess < secret:
    print("Too low!")
elif guess > secret:
    print("Too high!")
else:
    print("You got it!")

Python checks each condition in order:

• if — is the guess smaller? Then say "Too low!"
• elif (short for else if) — otherwise, is it bigger?
• else — if it is neither smaller nor bigger, it must be correct.

Indentation matters in Python. The four spaces before each print show that it belongs to the line above. Thonny and other editors add them for you after a colon (:).

Step 5: Keep guessing with a loop

Right now the player only gets one guess. A while loop repeats code while something is true.

import random

secret = random.randint(1, 100)
guess = 0
tries = 0

print("Welcome to the Number Guessing Game!")
print("I'm thinking of a number between 1 and 100.")

while guess != secret:
    guess = int(input("Your guess: "))
    tries = tries + 1

    if guess < secret:
        print("Too low! Try again.")
    elif guess > secret:
        print("Too high! Try again.")
    else:
        print(f"You got it in {tries} tries!")

• != means "is not equal to". The loop keeps going until the guess matches.
• We start guess at 0 so the loop runs at least once (0 can never be the secret).
• tries = tries + 1 adds one to the counter each time round.
• The f before the string makes it an f-string: anything inside { } is replaced by its value, so the player sees "You got it in 6 tries!".

Run it and play a few rounds. 🎉

Step 6: Don't crash on bad input

Try typing hello instead of a number. The program crashes with a ValueError, because int("hello") makes no sense. Real programs must cope with mistakes.

We can try the conversion and catch the error:

while True:
    text = input("Your guess: ")
    try:
        guess = int(text)
        break
    except ValueError:
        print("Please type a whole number.")

• while True loops forever — until we break out of it.
• If int(text) works, break leaves the loop with a valid number.
• If it fails, Python jumps to except ValueError and asks again instead of crashing.

Step 7: The complete game

Here is the finished program with input checking, a range check, a guess counter and "play again":

import random


def get_guess():
    """Ask until the player types a whole number from 1 to 100."""
    while True:
        text = input("Your guess (1-100): ")
        try:
            number = int(text)
        except ValueError:
            print("That's not a whole number. Try again.")
            continue
        if 1 <= number <= 100:
            return number
        print("Please choose a number from 1 to 100.")


def play():
    secret = random.randint(1, 100)
    tries = 0
    print("\nI'm thinking of a number between 1 and 100.")

    while True:
        guess = get_guess()
        tries += 1
        if guess < secret:
            print("Too low!")
        elif guess > secret:
            print("Too high!")
        else:
            print(f"Correct! The number was {secret}. You took {tries} tries.")
            return tries


print("Welcome to the Number Guessing Game!")
best = None

while True:
    score = play()
    if best is None or score < best:
        best = score
        print("That's your best score so far!")
    again = input("Play again? (y/n): ").strip().lower()
    if again != "y":
        print(f"Thanks for playing! Your best was {best} tries.")
        break

New ideas in this version:

• Functions (def get_guess(): and def play():) package code into named, reusable chunks. return sends a value back to wherever the function was called.
• The text in triple quotes under def get_guess() is a docstring — a note explaining what the function does.
• continue jumps straight back to the top of the loop.
• 1 <= number <= 100 checks that the number is in range — Python lets you write it just like in maths.
• tries += 1 is a shortcut for tries = tries + 1.
• best = None means "no best score yet". After each game we keep the smallest number of tries.
• .strip().lower() removes spaces and makes the answer lowercase, so Y, y and y all count as yes.
• \n inside a string starts a new line.

How to win every time (the computer science secret)

Is there a best strategy? Yes! Always guess the middle of the numbers that are still possible:

• Start with 50. "Too high" means the number is 1–49, so guess 25.
• "Too low" means 26–49, so guess 37, and so on.

Each guess cuts the possibilities in half, so you will always find the number in 7 guesses or fewer (because 2 × 2 × 2 × 2 × 2 × 2 × 2 = 128, which is more than 100). This strategy is called binary search, and computers use it to find things in huge lists incredibly fast.

Common errors and what they mean

Challenges to try next

1. Difficulty levels: ask "easy, medium or hard?" and pick a number up to 10, 100 or 1000.
2. Limited guesses: the player loses after 10 wrong guesses.
3. Hot or cold: if the guess is within 5 of the secret, print "🔥 Very hot!".
4. Swap roles: you think of a number and the computer guesses it using binary search.

What you learned

• Variables, strings and numbers.
• input() and int(), and why input must be checked.
• if, elif and else for decisions.
• while loops, break and continue.
• Functions with def and return.
• Handling errors with try and except.
• A real computer science idea: binary search.

If you have used Scratch before, you might notice these are the same ideas as Scratch's forever, if and variable blocks — just written as text. Our guide to Scratch vs Python explains how the two connect.

Frequently asked questions

What age should children start learning Python? Many children are ready around 10 or 11, once they can type comfortably and read instructions carefully. Younger children often start with Scratch.

Is Python free? Yes. Python and editors such as Thonny and VS Code are completely free.

Why does my game pick the same number every time I test it? It doesn't — random.randint picks a new number each run. If you set secret = 42 while testing, remember to change it back!