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Use rulers and yardsticks to find out exactly how long or tall your favorite toys are.
Have you ever wondered if your favorite toy car is longer than your favorite action figure, or if a giant stuffed animal is taller than your desk? Measuring helps us find the answer without even guessing!
To measure how long something is, we use tools with standard units. A ruler is a small tool used for short objects. Most rulers have two sides: inches and centimeters. An inch is about the length of a paperclip, while a centimeter is about the width of your pinky finger. Because centimeters are smaller, it takes more of them to measure the same object! When you start measuring, always line up the end of your object with the mark on the tool, not the very edge of the wood or plastic.
Let's find the length of a new pencil using the inch side of a ruler. 1. Place the eraser end of the pencil exactly at the mark. 2. Lay the pencil flat along the edge of the ruler. 3. Look at where the sharp tip ends. If it points to the number , the pencil is inches long.
Quick Check
Which number on the ruler should you line up with the start of your object?
Answer
You should always start at the 0 mark.
What if you want to measure something really big, like a rug or a doorway? A ruler is only inches long, which might be too small. That is when we use a yardstick. A yardstick is much longer than a ruler. In fact, yardstick is exactly the same as rulers put together! A yardstick measures feet, which is the same as inches. We use yardsticks for 'big' jobs and rulers for 'small' jobs like measuring a crayon or a spoon.
Imagine you need to measure two things: a postage stamp and a kitchen table. 1. For the stamp, a ruler is best because the stamp is very small (about inch). 2. For the table, a yardstick is better because the table is likely longer than inches. It would be hard to move a small ruler over and over again to measure a big table!
Quick Check
If you wanted to measure the length of a playground slide, would you use a ruler or a yardstick?
Answer
A yardstick, because a slide is a very large object.
Once we know the measurements, we can compare them to see which is longer or shorter. To find the difference between two objects, we use subtraction. If a toy truck is inches long and a toy car is inches long, we can find out how much longer the truck is by calculating . The truck is inches longer than the car. Always make sure you are using the same units (both inches or both centimeters) when you compare!
How many inches are in a standard yardstick?
Which unit is smaller?
A ruler is the best tool to measure the length of a whole classroom wall.
Review Tomorrow
Tomorrow morning, try to remember: How many inches are in a yardstick, and why do we start measuring at zero?
Practice Activity
Find three items in your room (like a book, a shoe, and a toy). Measure them all in inches and list them from shortest to longest!