Bigger Than A Foot

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SWBAT measure distances larger than a foot and translate the amount into inches.

Big Idea

Students need to go beyond memorizing 12 inches in a foot by using that information in measuring larger objects.

Warm Up

10 minutes

I begin today by asking how many inches in a foot? I ask them to write the number in their math journal. 

Well if there are 12 inches in a foot, would 18 inches be bigger or smaller than a foot? How about 9 inches? How much bigger than a foot is 21 inches? (I ask students to write the answer in their journals.) I ask for someone to share his/her answer. How do you know how much bigger it is? 

I repeat the process with "How much smaller than a foot is 8 inches? How do you know?"

I ask students to show me with their hands, about how big a foot is. (This is just a quick check for me if they have a conceptual idea of what a foot really is.

Teaching the Lesson

20 minutes

I invite students to come to the rug. I ask them how many feet long they think the rug is?   How could we find out? (Students may suggest using multiple rulers, moving rulers, or using a yard stick or measuring tape.) We employ the ways they suggest and compare our findings. We talk about any differences we may have found. (Moving the ruler or yardstick not exactly, reporting in inches and not in feet, etc.) 

I tell students that today I would like them to measure the height of a partner using a ruler and a yardstick. They will  have their partner stand against a wall and they will make a very light pencil mark to show the height. Next they will use the yardstick to find out how many feet and inches their partner is. They will record the answer on their paper and then repeat the process using a ruler. After they have recorded 2 measurements they will switch places and have their partner measure them. When they have finished measuring each other they will return to the rug.

I ask students whether it was easier to measure the larger item (themselves) using the ruler or the yardstick and why? I accept both answers with a logical reason. We talk about why some people may prefer the ruler and some the yardstick. I now ask them which do they think is more accurate. CC standards suggest that students should attend to precision (MP6) and the idea of which is more accurate supports this standard. It may be easier to measure with the ruler, but if we are not careful about marking an endpoint, it may not be as accurate as just moving the yardstick once. 

I ask how many inches in a yardstick? How many feet? Could we figure out how many inches in 2 feet? How would we do that? (repeated addition 12 + 12)  How about 4 feet? I record their ideas on the easel and allow volunteers to come up and show us their thinking on how they figured out the inches in 2 feet. 

I tell students that today we will be measuring in inches so we will need to remember that each ruler is 12 inches and the yardstick is 36 inches. (We can read these numbers right off of our tool to help us remember and we will record our measurements in inches.)

Independent Practice Centers

30 minutes

I tell students that we will be working in 3 groups for a little while. 

One group will be practicing measuring objects with a ruler. The objects are laid out, and there are recording sheets on the table. The objects include a board eraser, a dictionary, a paperback book, a crayon box, a stapler and a game box of about 18 inches in length. 

A second group will be measuring with a yardstick. There are several items for them to measure and record the size. They will measure the door, a chair, a desk and a bulletin board. 

The third group will be comparing sizes of things in inches. They will measure 2 objects and find out how much bigger the biggest object is. They will measure a crayon box, a pencil, a marker, a deck of cards, a matchbox car, a 6 inch teddy bear, and a piece of 12 x 18 construction paper.

I give the students a recording sheet for them to use as they move from center to center. I tell them they will have 10 minutes at each center. I rotate from center to center supporting students who may be struggling.


5 minutes

I ask students to clean up the area they are at and then return to their seats with their recording sheets for the day. I ask them on the back of one paper to write how many inches in a foot. I ask them to write how many feet in a yard and finally how many inches in a yard. 

I collect the papers and then we say together:

12 inches make a foot

A foot is like a book

If I add 3

Then what I see

Is a yard 

This isn’t hard.