How long is it?

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SWBAT express a length using multiple pieces of a shorter object.

Big Idea

My students have practiced measuring using non-standard units. This lesson opens a discussion why we get varying answers on the same item by using different units.

Rev Them Up

5 minutes

I want my students to start thinking about lengths. I will walk around the room, pick up two different items, and use them to compare and ask questions. 

Ex. I will pick up my pointer stick and a small book and ask, "Which is longer, my stick or the book? How do you know? Do you see anything in the room that is the same length as this book? How can you tell?" 

I will do this two more times with other items.

Whole Group Interaction

10 minutes

I will discuss with my students what we have done in the past to measure using objects. I will begin by asking:

Students what do we know about how to measure? How do you know that it works that way?

I will use Think-Pair-Share for this discussion. I will have them pair up with a partner before coming to our gathering spot. I will begin with the first question and give them time to talk to each other and then be ready to share with me. It will be much faster to hear 12 partners share than 24 students. Then, I will ask the second question. I will guide them towards giving me ideas related to:

  • Things must be lined up from tip to tip. 
  • We cannot get a correct answer if items are not aligned.

I want my students to understand measuring is a precise process and very specific actions must occur for the answer to be accurate. As the partners explain their reasoning I want them using mathematically appropriate vocabulary to explain their thoughts and actions in completing measurement tasks. (MP6). 

First Graders need to identify there is a need for a standard measurement tool. This can be identified by offering them multiple opportunities to measure the same item using different length units. (1.MD.A.2). I will need to make sure my students understand that when we use objects to measure with, there cannot be any gaps or overlaps


Independent Practice

10 minutes

Measuring stations will be set up. Each station will contain a big book and a different measuring tool: ceramic tiles, unifix cubes, q-tip, and popsicle sticks. Students will rotate through the stations and record their results. I will make sure the books are the same in size so that I can discuss what is happening with the results varying, even though the books are the same size. My goal is for them to state that the unit being used is different, so this will change the answer. If the units being used to measure with are not the same length, then the answers will vary. Watch this example video of one of my students measuring one of the big books.


10 minutes

I will apply a strip of  masking tape to the floor and ask students to walk by and measure using their feet, toe to heel. Discuss why are we all getting different answers?