Let’s Learn!
How do we measure an item to the nearest whole number?
Goal:
Goal:
Think About It!
Goal: Recall how to estimate length and to measure with a ruler to the nearest inch.
Ava wants to start her soccer banner. Ava’s teacher drew a line on the chalkboard to show how long each banner should be. How can Ava find out how long the line is so that she can measure her banner? She can estimate the length of the line and then use a ruler to find out!
Ava holding up a blank banner, she wants to measure it to find the length she needs.
A ruler is a measuring device that is marked with numbers along its edge. The numbers are units of measurement such as inches or centimeters. Ava needs to use inches, a customary unit for measuring length or distance. Today, we will use a ruler marked in inches to measure the lengths of various items. Length is the distance from one end of something to the other end. To find the distance from one end of the item to the other, we need to make sure that the 0 on the ruler lines up with one edge of the object. Then, we look to where the other edge of the object stops on the ruler. The black line above the ruler starts at 0 and ends at 6 on the ruler. The line is 6 inches long!
A ruler measuring a line. The line meausures 6 inches.
The line is 6 inches long
How can we find the length of an item if we do not have a ruler? We can estimate! If we know how long an inch is, we can look at an item and estimate how many inches long the item might be. Because we are estimating, our measurement will not be exactly right. It is okay to be within 2 inches of the correct measurement. When we estimate, we say an object is about a certain length.
Click each box to estimate the length of a poster!
A paper clip measures about one inch.
About 1 Inch
We need to know how long an inch is to estimate. An inch is about as long as a paper clip! When we estimate, we will not get out any paper clips to measure. We will imagine a paper clip’s length!
8 paper clips placed end to end measuring about 8 inches. The paper clips are placed on the side of the soccer poster and are being used to measure the poster.
About 8 Inches
To estimate, we think about how many paper clips we could put along the length of the poster. Ava thinks 8 paper clips could fit across the length of the poster. We put paper clips across the length of the poster to show you that she is right! The poster is about 8 inches long.
When we do have a ruler, an item we are measuring might not perfectly line up with a number on the ruler. We will measure the length of that item to the nearest whole number. This is estimation too! That means we will look for the number the edge opposite 0 is almost touching. Look at the black line below. One edge of the line starts at the 0 on the ruler. The other edge ends between the 4 and the 5. We will choose the whole number that the edge is closer to, 5. We will say that the line is about 5 inches long!
A ruler measuring a line. The line measures about 5 inches.
The line is about 5 inches long
Click each row to see how to measure the poster to the nearest whole number!
Measuring the side of the soccer poster. The corner of the poster is lined up at the 0 of the ruler.
Let's measure the poster with a ruler marked in inches. We will line up one edge of the poster with the 0 on the ruler.
Measuring the side of the soccer poster. The corner of the poster is lined up at the 0 the other edge of the poster measures closer to 8.
One edge is lined up with 0. The other edge is between 7 and 8 inches. Is the edge closer to 7 or 8? 8! That means the poster is about 8 inches long. 8 inches is the length Ava estimated!
Let’s use what we learned to estimate and then measure the line on the board for Ava!
There is a line. There is a arrow showing the start and an arrow showing the end of the line.
Here is the line Ava’s teacher drew on the board. There are arrows to show the start and end of the line.
There is a line. There is a arrow showing the start and an arrow showing the end of the line. There is a paper clip with the start of the paper clip lined up with the start of the line.
About how long do you think the line is? Imagine a paper clip. There is one above the line to help you imagine. Then click the Show Me button to see!
There is a line. There is a arrow showing the start and an arrow showing the end of the line. There are eleven paper clips lined up along the side of the line to measure the line.
The line is about 11 inches long.
Using the ruler to measure the line. The line starts at 0 on the ruler and ends between 11 and the 12 inches.
Now let's use the ruler to see how long the line is. The line starts at 0. It ends between 11 and 12.
Question
Does the line end closer to 11 or to 12?
The ruler lined up with the 0 on the ruler. The line is about 11 inches long.
The line ends closer to 11. The line is about 11 inches long. Ava's soccer banner needs to be about 11 inches long!
You can estimate and measure to the nearest whole number to find out about how long something is!