Welcome to Events and Responses! In the last series — Breaking Big Problems into Small Steps — you learned how decomposition turns a big, vague goal into a sequence of small, specific commands a computer can actually follow. Decomposition — breaking a big problem into smaller solvable pieces Each piece becomes a command — a clear, specific instruction Order matters — the sequence of commands must be correct Computers need complete, exact steps — they cannot infer or guess the missing parts That series answered: how do we turn a goal into instructions? But there is still something missing. When do those instructions actually run? Who or what starts them? Sometimes you start a program by clicking a button. Sometimes the program starts on its own when the clock hits a certain time. Sometimes a sensor detects something — heat, light, motion — and the program begins. These starting triggers are called events . And understanding them is the key to building interactive things — apps, games, smart devices, websites. What You Learned Last Time Idea What It Means ------ -------------- Decomposition Breaking a big problem into small, solvable steps Commands Each small step becomes a specific, exact instruction Sequence Steps must happen in the right order Precision Instructions must be exact — not vague or guessable What You Will Learn in This Series Post The Big Idea ------ ------------- What is an Event? Something that happens — a tap, a timer, a sensor — that a program can notice and respond to Events Are Everywhere Smoke alarms, automatic doors, phone notifications — events are all around you Events Inside Programs How programs "listen" for events and run the right commands when they occur Putting It All Together A complete event chain — from trigger to decomposed response The Light That Knows When You Walk In Have you ever walked into a shop and the lights turned on automatically before you even touched a switch? There was no one watching for you. There was no button to press. Something detected your presence and triggered an action. That something was an event . The event — motion detected — caused the lights to turn on. This is what this series is about: how computers notice things happening in the world, and what they do in response. Questions People Ask What is "event-driven programming" in plain English? It means a program starts up and then waits, instead of running through a list of steps and stopping. It reacts when something happens — a tap, a timer, a sensor. Nearly every app, website and game your child uses is built this way, which is why this idea is worth meeting early. My child already knows if-then and loops. Is this the same thing? No, and the difference is the useful bit. An if-then decision asks what should I do? An event asks when should I do anything at all? A child can write perfect instructions and still have no idea what makes them start running. This series answers that. Do we need to do the earlier series first? It helps but it is not essential. This series links back to the ideas it uses, so a curious reader can begin here. If you would rather go in order, start at How Computers Think. Does this connect to Scratch? Directly. Scratch blocks such as "when green flag clicked" and "when this sprite clicked" are event listeners — exactly what this series describes. A child who has read these four posts will recognise them straight away. How long does this series take? Four posts, each a 5–10 minute read plus an activity of ten to twenty minutes. Comfortably one afternoon, or one post a night across a week. A Note for Parents and Teachers This series teaches how interactive systems actually work: that a program mostly sits and waits, that something has to happen before anything runs, and that a response can itself become the next trigger. Children meet it through doorbells, smoke alarms, automatic doors and cash machines — things they already use without ever wondering what is going on inside. The best way to use it is to do the activities out loud, together. The one to pick if you only do one is The Chain Reaction in Events Are Everywhere: build a domino-style chain of household objects, write each link down as trigger, event and response, then find the one weak link that stops it. Children remember it because they built it, and it teaches event chains better than any explanation. In a classroom, each post works as a single lesson. Read it together, run the activity in pairs or small groups — The Human App in Events Inside Programs works especially well with a whole class, as each child holds one listener card — and close with the "Check Yourself" questions. Nothing needs to be installed, and no devices are required. This is series 4 of 6 in the Kids Programming learning path. New here? Start from the beginning. ✅ Start with the first post: What is an Event?