the ladder · rung 1 of 10
Level 1 · Light
Your first circuits — make light happen.
This is where every builder starts. A battery, a breadboard, an LED, and a resistor — four parts, one loop, one working light. Every level after this one keeps using the same parts, so nothing you learn here goes stale.
New in the box
- 3×AA battery pack (4.5 V) — The push that gets electrons moving. 4.5 volts — safe to touch.
- Solderless breadboard — Your building plate. Push parts in, pull them out, no glue, no solder.
- Jumper wires — The roads electricity travels between parts.
- Red LED (5 mm) — A tiny light with a one-way door — current only flows long-leg-in.
- Yellow LED (5 mm) — Like the red LED, in caution-light yellow.
- Green LED (5 mm) — Like the red LED, in go-light green.
- 220 Ω resistor — A speed bump for electricity. This one protects LEDs.
- 1 kΩ resistor — A bigger speed bump — about five 220s stacked.
- 10 kΩ resistor — A big speed bump, used for sensing tricks later.
- Slide switch — Opens or closes the loop. On means the loop is complete.
- Push button (tactile) — A switch that only stays on while you press it.
with everything through L1, your box now holds 11 component types.
Ideas this level teaches
- Circuits are loops — Electricity only flows around a complete, unbroken loop.
- LED polarity — LEDs are one-way doors: long leg to plus, or nothing happens.
- Ohm's law — Voltage = current × resistance. One equation, endless circuits.
- Switches — Breaking and completing loops on purpose — the root of all control.
- Series & parallel — Parts in a chain share voltage; parts side-by-side share current.
Projects at Level 1
First Light Build a real flashlight circuit and learn why every circuit is a loop. Morse Code Messenger A push button, an LED, and a secret code — send real messages with light. Twin Reds Two red LEDs on one loop — same current, half the leftover push, and a lesson in how voltages stack when parts sit end to end. Two Greens Twin Reds with green LEDs — bigger voltage bites, less leftover for the resistor, and a great lesson in how far a 4.5 V battery can actually push. Night Pin One 10 kΩ, one red LED, one slide — the simplest dimmer. A single big resistor runs the LED at 0.27 mA: invisible in daylight, perfect for a dark room. Tabletop Traffic Light Three LEDs on three parallel lanes, all lit by one switch — build a tabletop traffic light and discover parallel circuits. Bike Torch One yellow LED, two switches: a slide for a battery-friendly low beam, a push button for a bright flash, both lanes feeding the same lamp in parallel. Signal Pair Two push buttons, two LEDs, one battery — no sharing. Each button lights its own lamp with its own current, independent of the other. Dim Candle A 1 kΩ and a 10 kΩ in series throttle a red LED to a candle glow. Flip the bypass slide — the 10 kΩ gets shorted and the LED pops to a clear, steady glow. Three Sisters Three red LEDs side by side from one battery — each with its own 220 Ω — proving parallel lanes do their own Ohm's law and the battery adds the bill. One for All Three LEDs on ONE shared 220 Ω — the shortcut that fails. Red and yellow dim-split the current; green sits dark. Lesson: each LED needs its own resistor. Step Up Three 1 kΩ lanes in parallel into one red LED, each with its own slide switch. One slide = candle, two = glow, three = full lamp. The lanes stack. Longer Loop Three 1 kΩ speed bumps stacked end-to-end on one lane feed a single red LED. Resistors in series ADD up — the LED is throttled to a near-dark 0.87 mA. Bright and Dim Two red LEDs on one battery — one through 220 Ω (bright), one through 1 kΩ (candle). Same LEDs, two currents. The resistor sets each lane's brightness. Rainbow Loop Red, yellow and green LEDs on three parallel 220 Ω lanes under one slide. One flip lights all three, each lane running its own Ohm's law. Reserve Beacon A 10 kΩ in series with the LED keeps a dim always-on pilot glow. Flip the bypass slide — it shorts the 10 kΩ, and the pilot pops to full First-Light brightness. Short Cut First Light with a slide switch wired straight across the LED. Flip the slide and the LED goes dark even though the loop stays complete. The Vault Two buttons, one loop — the LED only lights when BOTH are pressed at the same time. Do Not Disturb Sign A green "chill" LED plus a switched red "leave me alone" LED — two lanes on one battery, and a switch that only touches one of them. Handhold Chain Three switches in a line — the LED only lights when all three are closed at once. AND, one step past The Vault. Two-Door Signal Two slide switches in parallel, one shared LED — either switch alone lights the lamp. The OR gate, at Level 1. Signal Light A slide switch and a push button in parallel — the slide is the steady beacon, the button is the extra flash. Either lights the lamp. Escape Hatch The Vault with a big red emergency button wired around both locks — turn BOTH keys, or hit the button, and the light comes on. The Brightness Lab Run a real experiment: predict, measure with your eyes, and prove Ohm's law.
What you can build so far
Every project at Levels 1–1 draws on the components you now own — earlier projects never stop being useful. With the full L1 box you can tackle any of these 24 projects:
🔦 First Light · 📡 Morse Code Messenger · 🎈 Twin Reds · 🌿 Two Greens · 🌙 Night Pin · 🚦 Tabletop Traffic Light · 🚲 Bike Torch · 🚦 Signal Pair · 🕯️ Dim Candle · 🔴 Three Sisters · 🥀 One for All · 📶 Step Up · 🪜 Longer Loop · 🔦 Bright and Dim · 🌈 Rainbow Loop · 🔆 Reserve Beacon · 🚫 Short Cut · 🔐 The Vault · 🚪 Do Not Disturb Sign · 🤝 Handhold Chain · 🚪 Two-Door Signal · 🚨 Signal Light · 🛟 Escape Hatch · 🧪 The Brightness Lab