Measuring with multiple tools

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Objective

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

Big Idea

My students have practiced measuring using non-standard units. This lesson allows us to discuss why we get varying answers about the same item by using different units.

Rev Them Up

5 minutes

I will begin by holding up a new un-sharpened pencil and use it to have them compare the length of different objects in the room to it. This will help my concrete thinkers have an entry point to this activity and allow them to understand visually what we are estimating and comparing the lengths of items in the room. After this I will continue on with different scenarios. I will say the following;

Students if you agree with what I say show me a thumbs up. If you disagree, show me a thumbs down. (If they seem unsure of these directions explain further, such as, if you think I am right show me thumbs up, if you think I am wrong, show me thumbs down.) 

This pencil is shorter than a backpack. (Thumbs up)

My hand is longer than the top of your desk. (Thumbs down)

This book is longer than a crayon. (Thumbs up)

My class comparing measurements video will show you some of the questions I proposed to my class and how they responded.

Whole Group Interactions

5 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?

I will guide them towards the following ideas:

  • Units must be lined up from tip to tip so that there are no gaps.
  • Units must not overlap
  • We cannot get a correct answer if units 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. (MP6). Mathematically proficient First Graders will check to be sure units are placed carefully to measure an object.

I also want to offer them multiple opportunities to measure the same item using different length units. (1.MD.A.2) to make connections between unit length and measurements. The end result is for First Graders to begin identifying a standard unit is necessary to get accurate measurements.

Independent Practice

10 minutes

In the independent practice section of the lesson, I want to make sure students have the opportunity to describe their ideas accurately as they complete their measurement tasks. As we went over in the discussion, first graders need to learn that measurement is an exact process and when using a tool to measure with there cannot be any overlapping or gaps. They also need to see the relationship between the changing length of the unit and the fixed length of the object being measured. Today, we will be measuring using multiple tools to do this. 

First, you need to print the Measure pencil worksheet.pptx and copy for each student. You will need to make sure they estimate first and fill in their answers for these estimates. I explain to my students:

An estimate is a good guess. It is not a time to be silly and make a guess that could in no way be true. I want you to really think about it and guess as close to the real answer as possible.

Also, I have to reiterate to my students more than once that they are not allowed to erase and change their estimate after we do the real measuring. Every year I have students who get upset because they want the estimate and the actual answer to match or they think I will count it wrong. I try to stop this from happening by telling them up front do not erase their estimate and it is okay if they do not match. I encourage them to check their estimation and then leave it alone as they begin to actually measure. Estimation with length is a skill that shows up in Second Grade Common Core.  The CCSS for this skill actually has estimation tied to standard measurement units; inches, cm, etc. I am using this lesson to give a general introduction to estimation for length.  I want them to begin analyzing objects visually and using this knowledge to determine possible units of length.  This will give them some information about estimation as they go into Second Grade and it really doesn't take a let time to cover it. 

Second, they will begin using the required measurement tools to actually measure the pencils on their worksheet. Students will be measuring using base ten blocks, unifix cubes, counters, and paper clips

Third, it is time for a discussion to occur.  My goal will be for them to see that we have a need for standard measuring units.  Every time they measure using different non-standard units the answer will vary. The pencils on the worksheet are all the same length, but the answers will be different because the measuring unit is different.  I will ask the following questions to help guide them towards this realization.

  • Look at your measuring answers. The pencils are all the same length. Did you get the same answer when you measured? (No their all different.)
  • Why? (Because the unifix cubes are longer then the cm cubes, you have to use more when their smaller.)
  • So is this giving us an accurate measurement? Why? (No because  were using all different things.)
  • What should be different? (Use the same thing every time.)

Closure

5 minutes

Print the closure question worksheet and copy for each student. When my students finish their measuring I will have them pick up the closure question and answer. I want them to answer in words and will remind them that one or two words is not a complete answer. I want to see what knowledge they have gained and reinforce having them explain their ideas of measurement with accurate vocabulary. This closure activity allows them more practice in explaining their reasoning. Check out this Closure answer pic and you will see an example of some of the answers I received. It really gave me insight on their thoughts and helped me determine who I needed to reteach.