Measure length using customary units

Length measurement assigns a numerical value by comparing an object’s length with equal customary units, selecting an appropriate unit—inch, foot, yard, or mile—and interpreting ruler or scale marks, including common fractional-inch increments. The relationships 12 inches = 1 foot, 3 feet = 1 yard, and 5,280 feet = 1 mile support estimation, comparison, and conversion; changing units changes the numerical measure but not the length itself. Metric units and advanced conversions involving compound or highly precise measurements are outside this scope.

Detailed Explanation: Measure length using customary units

To measure length, compare the object with equal-sized units. Choose a unit that fits the object:

Use inches for small objects.
Use feet for room-sized objects.
Use yards for longer distances, such as a playground.
Use miles for very long distances, such as between towns.

Example: Measure a pencil

Suppose you want to measure a pencil with a ruler.

Place the ruler next to the pencil.
Line up one end of the pencil with the ruler’s 0-inch mark.
Look at the mark where the other end of the pencil stops.
The pencil ends halfway between $4$ inches and $5$ inches. The halfway mark is $\frac{1}{2}$ inch.
Therefore, the pencil’s length is

4\frac{1}{2}\text{ inches}.

The number tells how many inches long the pencil is. If you measured it in a different unit, the number would change, but the pencil itself would still have the same length. Remember that $12$ inches equal $1$ foot, so $4\frac{1}{2}$ inches is less than $1$ foot.

Learn by doing: Measure length using customary units

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Measurement Conversion - Customary Length Units with Sub Units

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