LLMs · how ChatGPT works
Guess the next word
🎓 School maths · Years 7–8Probability — Pick outcomes by how often they occurred (frequency).Maths by year →
The Case. ChatGPT looks like magic, but its one trick is guessing the next word — again and again. Let's build a baby version.
Your tools. Plain Python learns which words tend to follow which, then chains guesses into a sentence.
Investigate. Press Run. Your tiny model writes a sentence by guessing one word at a time.
- Run it a few times — it wanders differently each time, like a real chatbot.
- Change the
textit learns from and it starts ‘talking’ about that instead.
your_code.py
Starting Python…
The Reveal
Starting Python… (first time only — a few seconds)
🗒️ Detective's notes
Bundles your findings, chart and code into one PDF you can keep, print or hand in.
🧩 How this code works
The tools it uses
- random — makes lucky, unpredictable choices — like rolling a dice.
What this one does
- • It uses chance and randomness.
- • It repeats a step many times with a loop.
How to read it, top to bottom
- 1. Import — bring in the tools (listed above).
- 2. The data — the lists and numbers near the top. These are the bits you change.
- 3. The work — a little maths, or a loop that repeats a step.
- 4. Show it —
print(...)writes words;plt.show()draws the picture.
Use it for your own problems
- Change the numbers at the top and press Run — nothing breaks, so experiment!
- Ask your own version of the question — swap in your family, your scores, your week.
- The same tools work on any numbers — that's the superpower you're learning.
Need a hint?
nxt['the'] is the list of words that came after 'the'. The model just picks one of them.