Measurement
A number or state reported by the sensor.
Topic Guide
Sensors
A sensor measures something in the physical world and gives the program a value to read.
Why this matters
A robot can measure distance, light, motion, temperature, touch, or sound. The readings vary, so students collect several before choosing the threshold that controls a response.
Beyond this topic
An automatic light receives a number from its sensor. The designer decides which readings count as dark enough, and the code compares every new reading with that threshold.
Math and logic
Threshold
The chosen value where the program changes its response.
Noise
Small fluctuations and errors in the readings.
Sampling
Taking new readings as the signal changes over time.
Small examples
Button
Report one of two states: pressed or released.
Distance
Estimate how far away an obstacle is.
Light level
Return a changing value as a space becomes brighter or darker.
Accelerometer
Report acceleration values that can indicate movement or orientation.
Program connections
Where this topic appears.
Active now
Robotics
Students write commands, wire simple circuits, read sensors, and trace physical cause and effect through the Sense–Decide–Act loop.
Coming later
AI & Smart Machines
A possible later program for testing patterns, predictions, prompts, mistakes, and the limits of AI tools.
Common mistakes
Expecting a fixed reading
Small fluctuations make the output flicker on and off.
Unhelpful threshold
The chosen boundary does not fit the room or task.
Skipping calibration
The program assumes every device and room gives the same values.
Giving the sensor too much credit
The component supplies a reading; the student's code decides what to do with it.
Put the idea to work
Robotics
Guided Project
Button and Buzzer Alarm
Connect a button to a visible and audible alarm, then write clear rules for arming, triggering, and resetting it.
See how it works
Robotics
Guided Project
micro:bit Reaction Timer
Build a reaction timer with a random delay, an early-press rule, and results in the correct units.
See how it works
Robotics
Computer Lab Project
Robot Patrol Challenge
Design a repeating patrol that notices an obstacle, tries a response, and checks whether the response worked.
See how it works