What are dual units?

Dual units are two different ways to measure the same thing, just like how you can use both inches and centimeters to measure a toy's length.

Imagine you have a bag of candy. You know it has 20 pieces, but your friend counts them differently, she sees 10 pairs of candies. Both of you are right! You're just using different units to describe the same amount of candy.

Think about money: if you have 4 quarters, that’s the same as having $1. Quarters and dollars are like dual units, they’re different ways to express the same value. You can use one or the other depending on what makes sense in the moment.

Sometimes, one unit is easier for big numbers, and another is better for small ones. Like how we might say a car travels 60 miles per hour instead of 96.5 kilometers per hour, even though they’re both talking about speed.

Dual units help us switch between different ways of seeing the same thing, just like you can count your candy as single pieces or in pairs!