Level 5: Coordinate units to constitute a scale.
5D
Account for change of origin when measurement does not start at zero. (Zero-Point: Any number can serve as zero.)
"I can start to measure from the 3 on the inches ruler, and take off 3 inches from the result." (Note: Starting at 2 or 3 is generally more difficult than starting at 1. Starting at a non-whole number is more difficult still).
"If I start at 3 and go to 71/4 , the measure is 41/4 ." (Note: Shifts involving fractions are usually more difficult than those with whole numbers.)
Broken Ruler
Assessment