AI Tutor
Imagine you jump 6 feet in gym class, while your friend jumps 2 yards. Who jumped farther?
You can't just compare the numbers 66 and 22 because they are in different units. To compare or combine measurements, you must first convert them into the same unit.
How do we change larger measurement units into smaller ones when solving everyday problems?

Customary Unit Conversions

In the US customary system, larger units break down into smaller units by multiplying. Since 1 yard=3 feet1\text{ yard} = 3\text{ feet}, you multiply the number of yards by 33 to find the total feet.
Let's solve a word problem: Maya builds a wooden fence that is 4 yards4\text{ yards} long, and her brother adds another 5 feet5\text{ feet} to it. What is the total length of the fence in feet?
First, convert the yards to feet: 4 yards×3=12 feet4\text{ yards} \times 3 = 12\text{ feet}. Then add the remaining feet: 12 feet+5 feet=17 feet12\text{ feet} + 5\text{ feet} = 17\text{ feet}.
A common mistake is adding the numbers straight across without converting: 4+5=94 + 5 = 9. But 4 yards4\text{ yards} and 5 feet5\text{ feet} are different sizes, so adding them directly gives the wrong answer.
What happens when we measure distances using the metric system instead?

Metric Distances on a Number Line

The metric system uses powers of 1010, making conversions simple. There are 100 centimeters100\text{ centimeters} in 1 meter1\text{ meter}, and 1,000 meters1{,}000\text{ meters} in 1 kilometer1\text{ kilometer}.