C4T free concept simulator
Browser State Concept Simulator
Explore course concepts through adjustable values, prediction, deterministic feedback, and an explanatory trace.
This free concept simulator supports guided prediction, comparison, and reflection. It does not execute code, train models, run databases, create repositories, or replace full project software. The course's always-free pathway also explains how to create project files with freely installable or open tools; paid services and physical hardware remain optional.
Free concept simulator
Browser State Concept Simulator
Explore course concepts through adjustable values, prediction, deterministic feedback, and an explanatory trace.
1 · Predict
How many columns will the card grid use at this viewport width?
2 · Explore
The simulated browser width.
Items placed into the responsive grid.
3 · Inspect the result
Ready to simulate
Choose a prediction, adjust the controls, and run the lab. The displayed result comes from the simplified values and rules on this page.
Courses using this free concept lab
Lab ID: javascript-lab. The guided controls run in your browser; this page does not execute course code or connect to external hardware, model, database, or deployment services.