Putting It All Together: From Big Problem to Small Commands You have learned the core skill of this series. Let us see it in action — fully, from start to finish. What You Learned Post The Big Idea ------ ------------- What is Decomposition? Breaking a big problem into smaller pieces that are each easier to understand and act on Decomposition in Everyday Life You already do this constantly — getting ready, cooking, travelling Why Computers Need Small Steps Computers follow one specific instruction at a time — big vague goals are not instructions A Complete Example: Making a Cup of Tea Let us take one real goal and decompose it all the way down to the level of commands a computer could follow. The Goal > "Make a cup of tea" First Level of Decomposition 1. Boil the water 2. Prepare the cup 3. Brew the tea 4. Add milk and sugar if needed Better — but these are still too big. Let us go deeper. Full Decomposition Boil the water: 1. Fill the kettle with cold water (at least 300ml) 2. Place the kettle on its base 3. Press the On button on the kettle 4. Wait until the kettle clicks off (water is boiling) Prepare the cup: 5. Take a clean mug from the cupboard 6. Place one tea bag into the mug Brew the tea: 7. Pour the boiling water into the mug, filling it to about 2cm from the top 8. Wait 3 minutes (letting the tea brew) 9. Remove the tea bag by pressing it gently against the side of the mug with a spoon 10. Discard the used tea bag Add milk and sugar: 11. If milk is desired: pour approximately 50ml of cold milk into the mug 12. If sugar is desired: add one teaspoon of sugar 13. Stir the tea for 10 seconds The Result: 13 specific, exact commands Each one is: ✅ Specific (only one correct way to carry it out) ✅ Achievable (a robot or program could do this step) ✅ In the right order (changing the order would break things) "Make a cup of tea" is now a program. The Decomposition Checklist When breaking down any problem, ask: 1. What are all the things that need to happen? (List them) 2. Is each step specific enough to act on? (Or does it need more breaking down?) 3. Are the steps in the right order? (Would changing the order break anything?) 4. Are there any steps I assumed, but did not write? (Computers cannot assume) Run through these questions for every decomposition before calling it done. Why This Matters for Everything Ahead You now have two powerful skills: 1. Commands — you know what an individual instruction looks like and what makes it good 2. Decomposition — you know how to break any goal into a sequence of those instructions Together, these let you take any real problem and work out what commands are needed to solve it. But there is still one question we have not answered: What actually starts those commands running? You press a button. The door opens automatically. Your alarm goes off at exactly 7:30 AM. Something triggers the sequence of commands to begin. Those triggers are called events — and they are what the next series is about: Events: When Something Happens → Action. 🎯 Try This Yourself The Hidden Tower Two players, two identical sets of objects, and something to hide behind — a big book propped up, or sit back to back. Building blocks are ideal, but six coins, five cups and a spoon work just as well. 1. Both players take the same objects. Check they match exactly. 2. Player One builds something behind the screen. Nothing fancy — six or seven pieces is plenty. Player Two must not see it. 3. Player One now writes numbered instructions so that Player Two can build the identical thing. Writing only; no talking, no pointing, no questions. 4. Hand the list over. Player Two follows it exactly and builds. 5. Lift the screen. Compare. What to watch for: they will not match, and the gap is always in the same place — the step that was assumed. Which way round? How far along? Which of the two red blocks? Run the decomposition checklist over your list, fix it, rebuild, and keep going until the two towers are twins. That is exactly the loop a programmer lives in. 🤔 Check Yourself 1. "Boil the water" was one step, then it became four. Why was one step not enough? Because "boil the water" does not say to fill the kettle, put it on its base, press the button, or wait for the click. It is a goal wearing the costume of a step . Decomposition keeps going down levels until nothing is left hiding inside. 2. Which question in the decomposition checklist catches the most mistakes? Usually the last one: are there any steps I assumed but did not write? Everything you find obvious is a step you are likely to leave out — and computers cannot assume. They only have what you wrote down. 3. You have a perfect list of thirteen commands for making tea. What is still missing? Something to start it. A list of commands just sits there until something sets it running — a button pressed, a time reached, a door opened. Those triggers are called events , and they are the whole of the next series. 🔑 Words You Just Learned Word What it…