Imagine that you are grocery shopping and you stop to pick out delicious looking berries. The sign says “Sale: Strawberries $4.99 per pound.” You select some, place them in a container, and then put them on the scale. At first, the scale reads 0.95 pounds; then it changes to 1.2 pounds. You remove the container and place it on the scale again and it reads 1.5 pounds.
How close are these measurements to the actual weight of the strawberries? Do you get the same measurement each time that you weigh them? These questions are important when it comes to knowing if you have enough money to purchase a specific amount of produce, but also in making measurements in science.
Measurements provide quantitative information that is critical in studying science. Each measurement has an amount, a unit for comparison, and a degree of uncertainty. In this lesson you will learn how to correctly reflect the uncertainty in measurements.
Question
Why must a measurement include both a number and a unit?
For a measurement to be useful, it must include both a number and a unit. Measurements provide information of quantity. If they do not include a unit, you cannot be sure of the information the number provides. For example, 12 could mean 12 people, 12 meters, 12 minutes, etc.
