Let’s Learn!

Think About It!

Goal: Recognize half inches on a ruler and how to measure to the nearest half inch.

Logan is looking for a tennis racket. He needs a racket that is about 21 inches long. How can we help him find which racket is the right size?

Logan with the three different sized tennis rackets. We are going to measure to find out the right size tennis racket for Logan.

We can measure the length of each racket to help Logan! Length is the distance from one end of an object to the other end. We will use an inch ruler to measure the length of an object. When we measure an object, we line one end of the object up with the 0 line on the left end of the ruler. Then we look for where the other edge of the object falls along the ruler.

Logan looked at the ruler and saw lines between the inch lines. He was curious about what they are. He began to think about what happens if an item measures between two numbers on the ruler. You can measure to the nearest half inch! You may have measured to the nearest inch by looking at which number the end of an object was closer to on the ruler. Now you can measure to the nearest half inch. There are lines between each number on the ruler. The longest line that is between two numbers is the half-inch mark. A half inch is half of an inch. That is why the half-inch line is between two inch lines on the ruler.

A ruler showing the 1 inch marker and the 2 inch marker. The Longest line between the two numbers is the half inch mark. It is circled in red.

This is the half-inch line!

Measuring to the nearest half inch is just like measuring to the nearest inch. This gives us a measurement we can use if an object does not extend evenly to the next number. Sometimes objects do not measure exactly to the next inch, so we need a smaller measurement to get a more precise measurement. To measure to the nearest half inch, look at where the item ends on the ruler. Instead of deciding between one number and another, you will decide between one of the numbers and the half-inch line. If the item ends closer to the half-inch line, you will take the number on the left and put “ \(\frac{1}{2}\) ” next to it. If the item ends closer to one of the numbers, you will just write the number without “ \(\frac{1}{2}\) .” Write “about,” then the measurement you found, and the unit “inches” to show your answer!

A tennis racket lined up with a ruler. The very end of the handle is lined up with the zero on the ruler.

Let’s measure the length of the red racket with an inch ruler. We will line up one edge of the racket with the 0 on the ruler.

A tennis racket lined up with a ruler. The very end of the handle is lined up with the zero on the ruler. The other end of the tennis racket lines up with the half inch line after twenty three inches.

One edge is lined up with 0. The other end of the racket is between 23 and 24 on the ruler.

A close up view of the ruler after meausring the tennis racket. The measurement is between the 23 and the half inch line

Now find the half-inch line. We can see that the end of the racket is between 23 and the half-inch line.

Is the end of the racket closer to 23 on the ruler or to the half-inch line between 23 and 24? It is closer to the half-inch line! That means the red racket is about \(23\frac{1}{2}\) inches long. That is too long for Logan!

Let's use what we have learned to measure one more racket for Logan!