Three Blocks Build Everything
🎯 Today's mission briefing
We are learning the three building blocks every program in the world is made from — sequence, selection and iteration — so we can read, write and check an algorithm without needing a computer to tell us whether it works.
You'll know you've got it when:
- I can explain sequence, selection and iteration and give a real example of each from my own house
- I can build an algorithm from block cards, including at least one IF/ELSE and one REPEAT
- I can desk-check a script line by line and find a bug before anything runs
The claw machine at the show
Connects to what your guest already knows and makes them curious. Activating prior knowledge is one of the strongest predictors of new learning.
You've stood in front of one. Lights, music, a mountain of plush toys, and a claw that grips your prize with all the strength of a wet noodle. It feels like a machine with a personality — a mean one. It isn't. That claw machine has no personality, no plan and no opinion about you. Its entire brain is three ideas, over and over: do these steps in this order, choose between two paths, and repeat until something happens. That's it. That's also your favourite video game, the traffic lights outside the shops, the self-checkout, and every app on every phone you've ever held.
Before you read on, try this out loud with your helper: describe the claw machine's behaviour from the moment you put the coin in. Where does it do things IN ORDER? Where does it CHOOSE? Where does it REPEAT? You'll get most of it. You've been reading programs your whole life without knowing the words.