📏 Number Line Explorer
Skill goal: build magnitude sense for integers and fractions, and see how an inequality shades a whole ray of numbers.
Observe
Every point on the number line is a number. Right means bigger, left means smaller. Drag the blue dot — where does −5 sit compared to 3? Where does 1/2 sit?
Manipulate
Predict
Before you change it, what do you think will happen? If you drag the dot from 2 to −2, does the value get bigger or smaller? In Inequality mode, what changes on the number line when you switch from < to ≤?
See
Explain
Why it works: on a number line, position is size — farther right always means greater. An inequality like x < 2 is true for infinitely many numbers, so we shade the whole ray; an open circle means the boundary itself is left out, a filled one means it counts.
Challenge
1. Switch to Integers mode and drag the blue dot to −6, then press Check.
2. Switch to Inequality mode and make the number line show x ≥ 3, then press Check.