Texas Math Models

Try “number line” or “4.5D”

The benchmarks

right, straight, acute, obtuse

G4

Measure every angle against a square corner before you touch a protractor.rightexactly 90°straightexactly 180°the two you should know on sightacuteless than 90°obtusemore than 90°compare the angle, never the length of its raysan estimate costs a second and catches a reading that is badly wrong

How this one works

How

ask first: is it smaller than a square corner, the same, or bigger?

Best when

always, before you measure. It catches a wrong reading.

The same problem, other ways