Signal
A piece of information the program can inspect.
Curriculum topic
Sensing and Collision
Sensing gives a program information about contact, distance, colour, input, or another changing part of the world.
Why it matters
A small idea that returns in larger systems.
Movement alone does not create interaction. Games become systems when they notice walls, hazards, targets, or players. Robots become responsive when they can measure something outside their command list.
Real-world connection
A door sensor, a phone screen, and a game hitbox all decide whether an interaction occurred. The measurements differ, but each must define what counts as contact.
The connection shows where the idea returns; it does not claim every advanced application is taught in this first topic.
Math and logic kernel
The structure beneath the project.
Collision
Two regions overlap or touch.
Boundary
A position or region that changes the rules.
Continuous checking
Changing inputs must often be tested repeatedly.
Small examples
Make one relationship visible at a time.
Touching colour
Treat a map colour as a wall or hazard.
Sprite collision
Detect contact between player and target.
Distance reading
Respond when an object is nearer than a threshold.
Button sensing
Turn a physical action into a program signal.
Program connections
Where this topic appears.
Active now
Scratch & Game Design
Beginner-friendly programming through original games, animations, simulations, and interactive stories.
Active now
Robotics
Commands, sensors, simple electronics, simulations, and physical systems organized around Sense, Decide, Act.
Available later
Roblox Studio / Lua
A future bridge from visual programming to Lua, 3D objects, events, and larger game systems.
Common mistakes
Useful clues, not reasons to stop.
Oversized collision area
Transparent or hidden parts of a costume trigger contact.
One-time check
Fast movement passes through because collision is not checked continuously.
No response state
Contact is detected repeatedly and score increases many times.
Visual guess
The student assumes objects touch instead of inspecting the sensing result.
Lesson and projects
Use the idea inside a working system.
Scratch & Game Design
Guided Class Project
The Floor Is Definitely Lava
Build a compact platform game where collision, jumping, safe surfaces, and game state must agree.
Open project
Scratch & Game Design
Computer Lab Project
Astro-Chicken Rescue
Collect drifting space chickens while tracking several positions and avoiding danger zones.
Open project
Robotics
Guided Class Project
Button and Buzzer Alarm
Connect a button input to visible and audible outputs, then improve the alarm's state rules.
Open project