What you'll build
Read how bright the room is using an LDR sensor.
Before you start
You'll learn: analogRead() turns a sensor voltage into a number from 0 to 1023, and Serial.println() lets you watch it live.
You'll finish: A light sensor (LDR) that prints live brightness values to the Serial Monitor.
Real world: Phones dimming their screens and street lights switching on at dusk start with exactly this reading.
Then try: Map the numbers to 'dark / dim / bright' in words, or log a whole day of sunlight for a garden spot.
Who does this: Instrument technician or data technician — TVET instrumentation, or a path into data science.