# Comparing Lengths Using Standard Units

Content Comparing Lengths Using Standard Units
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Comparing Lengths Using Standard Units
CCSS.MATH.CONTENT.2.MD.A.4

## Basics on the topicComparing Lengths Using Standard Units

You and your friend made paper airplanes today! Now you can't wait to see how they fly. But first you want to measure your planes to see whose paper plane is longer. In this text you can learn about how to measure and compare lengths so that you can determine which plane is longer.

## Comparing Lengths (2nd Grade) – Measuring

Let’s learn more about length differences of about 1 ft and how to measure them with the following explanation. When we compare the length of two objects, we are determining the difference between how long they are. They can be longer, shorter, or the same. We can subtract the two measurements to find the difference in length.

To compare the lengths, we will need to use a standard unit of measure, like an inch or centimeter, and a special tool, like a ruler. Let's start by using the side of this ruler marked inches.

First, we will measure the length of this piece of paper by lining it up along the ruler and recording eleven inches.

Next, we will measure the length of this tape by lining it up along the ruler and recording four inches.

## Comparing Lengths – Subtracting Equation

Then, we will set up our subtraction equation using the measurements. Larger measurement minus smaller measurement equals the difference. So we write eleven minus four equals.

Now we can solve and label our answer with the correct unit, inches.

Eleven minus four equals seven, so the answer is seven inches. We can say that the paper is seven inches longer than the tape or that the tape is seven inches shorter than the paper.

## Comparing Lengths (2nd Grade) – Summary

When you need to compare lengths, find a ruler indicating a standard unit of measure, like inches or centimeters. Then all you need to do is the following:

Step # What to do
1 Measure the length of both objects.
2 Write the subtraction equation: Larger
measurement minus smaller measurement
equals the difference.
3 Solve and label the answer with the correct
unit of measurement.
4 Now you can state the comparison: object A is
blank inches/centimeters longer or shorter
than object B.

Have you practiced yet? On this website, you can also find interactive exercises for comparing lengths in 2nd grade as well as worksheets with word problems and further activities.

### TranscriptComparing Lengths Using Standard Units

Freddie and Zuri made paper airplanes today! They can't wait to see how they fly. But first they want to measure them to see who’s paper plane is longer. Let's help them by learning about "Comparing Lengths Using Standard Units''. When we compare the length of two objects, we are determining the difference between how long they are. They can be longer, shorter, or the same. We can subtract the two measurements to find the difference in length. To compare the lengths, we will need to use a standard unit of measure, like an inch or centimeter, and a special tool, like a ruler. Let's start by using the side of this ruler marked inches. First, we will measure the length of this piece of paper by lining it up along the ruler and recording eleven inches. Next, we will measure the length of this tape by lining it up along the ruler... and recording four inches. Then, we will set up our subtraction equation using the measurements. Larger measurement minus smaller measurement equals the difference. So we write eleven minus four equals. Now we can solve and label our answer with the correct unit, inches. Eleven minus four equals seven, so the answer is seven inches. We can say that the paper is seven inches longer than the tape or that the tape is seven inches shorter than the paper. Now that we have compared our first two objects, let's help Freddie and Zuri with their paper planes. This time, let's flip the ruler over and use the side marked centimeters. It doesn't matter which side we use as long as we measure both objects we are comparing with the same unit. First, we will measure the length of Freddie's airplane and record twenty one centimeters. Next, we will measure the length of Zuri's airplane and record thirty centimeters. Then, we will set up our subtraction equation using the measurements. Remember, the larger number goes first, so we will write Zuri's measurement, thirty, minus Freddie's measurement, twenty-one, equals. Now we can solve and label our answer in centimeters. Thirty minus twenty-one equals nine, so the answer is nine centimeters. We can say that Zuri's plane is nine centimeters longer than Freddie's or that Freddie's airplane is nine centimeters shorter than Zuri's. Before we see if their airplanes can fly, let's remember! Today we learned about comparing lengths using standard units! When we compare the length of two objects, we are determining the difference between how long they are. Using a ruler and standard unit of measure, like inches or centimeters, first, measure the length of both objects. Then, write the subtraction equation: Larger measurement minus smaller measurement equals the difference. Lastly, solve and label the answer with the correct unit of measurement. Now you can state the comparison: Object A is blank centimeters longer or shorter than object B. "I guess the length of our airplanes doesn't really matter, Freddie." "Yeah, they both fly great!" "Ouch!"

## Comparing Lengths Using Standard Units exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Comparing Lengths Using Standard Units.
• ### Which paper airplane is shorter? Which is longer?

Hints

We can use the measurements noted on the rulers to tell which paper airplane is longer and which is shorter.

The longer paper airplane will have a larger number as the measurement. The shorter paper airplane will have a smaller number as the measurement.

Solution

If you said that the blue paper airplane is shorter and the red paper airplane is longer, you are correct!

If we look at the lengths measured by the rulers, we will see that the blue airplane is four inches and the red airplane is ten inches long. Since the red airplane measurement is bigger, the red airplane is longer than the blue airplane.

• ### What do you know about comparing length measurements?

Hints

Remember, we already know the lengths of objects after we have measured, so that can't be one of the answers.

Use the image here to help visualize the formula!

Solution

When trying to find the difference in length between two objects, the larger length measurement minus the smaller measurement equals the difference in length. Then, we can use phrases like "Object A is smaller than Object B" or "Object B is larger than Object A" to describe the difference in length.

• ### Which leaf is longer? What is the difference in length?

Hints

The longer object will have a larger number as its measurement.

Solution

The longer leaf is the orange leaf, because it has a length of 5 inches compared to the length of the green leaf (2 inches). The difference is length was calculated using the larger measurement - smaller measurement = difference formula:

5 inches - 2 inches = 3 inches

So, the orange leaf is 3 inches LONGER than the green leaf.

• ### What is the best description of the length comparison?

Hints

Use the image pictured here to help you figure out the correct difference in length!

Remember, the red pencil is LONGER than the blue pencil.

Solution

Using the image, you were able to complete the following problem:

22 centimeters - 17 centimeters = 5 centimeters difference in length

While many of the statements LOOK very similar, we know that the red pencil is the larger object and the difference in length is 5 centimeters. So, the correct statement is the red pencil is 5 centimeters LONGER than the blue pencil.

• ### What is the correct difference in length?

Hints

Remember, the formula to use is the larger measurement minus the smaller measurement equals the difference in length.

The larger measurement in this case is 10 inches and the smaller measurement is 6 inches.

Solution

When we look at both of these objects, the red plane is 10 inches long and the blue plane is 4 inches long. Using that information, we can use the formula pictured here to find the difference in length:

10 inches - 4 inches = 6 inches

So the blue paper airplane is 6 inches longer that the red paper airplane.

• ### Can you compare the length of the pens?

Hints

Remember to use the formula pictured here to figure out the difference in length.

Be careful as you read each sentence to decide which is the correct comparison. We can describe the objects as longer and shorter than the other.

Solution

When looking at the measurements on the rulers, we can see that the purple pen is 14 centimeters long and the black pen is 9 centimeters long. So the purple pen is the longer than the black pen. But by how much? if we use the formula, we would get the following:

14 centimeters - 9 centimeters = 5 centimeters

So, the sentence that best compares the length of the purple and black pens is The black pen is 5 centimeters shorter than the purple pen.