JJ.3 Choose the appropriate customary unit
What are customary units?
Customary units are the units of measurement used most often in the United States to measure length, weight, and volume. These units help us describe how long, how heavy, or how much something is.
- Length: inch, foot, yard, mile
- Weight: ounce, pound
- Volume: cup, pint, quart, gallon
We use customary units in everyday life, such as when measuring a desk, weighing groceries, or pouring liquids while cooking.
How to choose units for length
To choose the correct length unit, think about the size of the object you are measuring. Smaller objects use smaller units, while larger distances use larger units.
- Use inches to measure something small, like a crayon.
- Use feet to measure something medium-sized, like the height of a table.
- Use yards to measure something larger, like the width of a playground field.
- Use miles to measure long distances, like the distance between two towns.
If you would need many small units to measure an object, switch to a larger unit to make the measurement easier to understand.
How to choose units for weight
Weight tells how heavy something is. Choose the unit that best matches the object’s heaviness.
- Use ounces to measure something light, like a slice of bread.
- Use pounds to measure something heavier, like a backpack or a pet.
If the object is very light, ounces are usually the better choice. For most everyday items, pounds are easier to use.
How to choose units for volume
Volume tells how much liquid a container can hold. Pick the unit based on the size of the container.
- Use cups for small amounts of liquid, like a serving of juice.
- Use pints or quarts for medium amounts, like a container of milk or soup.
- Use gallons for large amounts, such as a jug of water.
A larger container usually needs a larger unit. Choosing the right unit helps measurements stay clear and easy to compare.
Using customary units in real situations
In real life, we pick a unit based on what makes the most sense for the measurement. The goal is to choose a unit that is reasonable and easy for others to understand.
- Measuring the length of a book: feet (reasonable size)
- Weighing apples at the store: pounds (common and practical)
- Filling a water bottle: cups or pints (not too big, not too small)
Ask yourself: “Which unit gives a measurement that makes sense for the object?” If the number feels too big or too small, try a different unit.