Using Different Units to Measure Day 1

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Objective

SWBAT use accurate measuring techniques. SWBAT measure lengths using different size units.

Big Idea

Today students will focus on the idea that measuring an object using different length units will result in different measurements.

Warm Up

5 minutes

I gather the students on the carpet and have them face the number grid.  I am using a 101-199 number grid, to work on rote counting bigger numbers.  The CCSS expect that students can count to 120, starting at any number less than 120.  This activity allows for you to check for students both meeting and exceeding the standard (CCSS.Math.Content.1.NBT.A.1). 

"We are going to count from one number to another.  Sometimes we will count forwards and sometimes we will count backwards.  I am going to put this green card in front of the number 101.  Who can tell me a number we should put this red card in front of?"

I take a student response and then ask another student to come up and place the card in front of the suggested number.  This allows me to choose someone who I want to check and see if they can find the given number.  

I then go over where we will start and stop and ask if we are counting up or down?  I also go over the reason why we don't say the word "and" when we are reading big numbers, which is because we don't want to read the number as though it is a fraction or decimal and set students up for misconceptions when they start learning about these concepts.

Looking At Results of Student Steps

10 minutes

I start off by gathering the students on the carpet and have the face the easel.  

"Yesterday we measured different length floor strips with our own feet or 'student steps'.  We focused on which strips were longer.  Today, we will look at the actual steps it took to measure some of the strips.  How many steps did it take you to go from my desk to the chair and how many steps from the desk to the chair?  I want you to look at your recording sheet (from yesterday's lesson) and tell me what you wrote down for each one.  I will record your results on the easel (see picture in section resource)."

Since the students have different size shoes, there will inevitably be different measurements for the same strip.  This will be your starting point for the next part of the conversation.

"Why do you think that we got different measurements for the same strip?"  Although ideas of miscounting or not starting and stopping at the each end will be offered, you will want to focus on the idea that measuring with different size units will result in different measurements.  The Core Standards expect students to construct viable arguments and critique the reasoning of others.  They can justify their conclusions, communicate them to others, and respond to the arguments of others. They reason inductively about data (CCSS.Math.Practice.MP3).

To reinforce this concept and eliminate the idea that someone miscounted or was careful with their measurement, I call up someone with small feet to measure the line and then record the measurement.  I repeat the prices swift a student that has bigger feet.

"We know that they both just measured carefully and didn't miscount or measure incorrectly.  Some of you said that the size of the foot would make a difference.  Today you will find out more about this idea during the measuring activity."

Measuring with Craft Sticks, Playing Cards, and Index Cards

45 minutes

*You will need to use the floor strips that were laid out in the  previous lesson.

Advanced Preparation:  You should make enough copies of the recording sheet (section resource) for your entire class.  You should also make 8 posters (one for each floor strip) that will be used for students to record their measurements.  There is a video, in the section resource (Poster Set Up), that shows you how to create these.  Each poster should have the heading Floor Strip #___.

"Today you will measuring some of the floor strips that you used yesterday.  Instead of using student steps, you will use three different units today.  You can choose from craft sticks, index cards, or playing cards (there is a video of this introduction in the section resource).  Who can demonstrate how to measure the appropriate way with the craft sticks?" I then call on a student to do so.  Again, the mentioned clip has this modeling too.  Mathematically proficient need to communicate precisely to others. They are careful about specifying units of measure, and labeling axes to clarify the correspondence with quantities in a problem. They calculate accurately and efficiently, express numerical answers with a degree of precision appropriate for the problem context (CCSS.Math.Practice.MP6).

"You will also use this recording sheet (display one of the copies that you made) to record your results."  Let's look at the sheet together."  You should go over how to fill it out the sheet.  "You will need to measure each strip twice, using a different unit each time.  Once you have measured the strip, you and your partner should also record your results on the posters that are on the middle table." I also model this for them as well.  It is important that they record the measurement and the unit used.  There is a photo in the section resource of a student filling out the poster and an example of a completed recording sheet.  

You will spend the next two days working on this activity.

I also modeled how to have two groups working on the same strip at the same time. There is a video (Two Groups at the Same Time)  of this in the section resource.  This will help you see how to set this up. 

As students are working, you will want to observe:

  • Are students using appropriate measurement techniques (there are a few pictures and videos int he resource section that model these techniques)?
  • How are they handling 1/2 measurements?

This activity is allowing students to express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps. (CCSS.Math.Content.1.MD.A.2).

Continued Practice

10 minutes

I will end this lesson with another story problem. This one will involve a subtraction situation.  I will call the students back to the carpet and go over the problem as a class.  I ask them to visualize the action in the story as I read it aloud.  "Who can tell me what is going on in this story?"  I call on a couple of students.  I now want you to go and work on this problem on your own. Make sure that you represent your thinking and write an equation."

I continue to work on problem like this to keep the students skills sharp as we continue to work on this unit on measurement.