Standard and Non-Standard Units of Measurement

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SWBAT identify a standard and non-standard unit of measure and use these tools to find the length of different objects.

Big Idea

Understand the measurement process and the need for standard units.


5 minutes

We have learned about fractions, and fractions on a number line, so now I want to show you a tool we use all the time that shows us fractions on a number line and also helps us measure…..a ruler.

Here we discuss why we need rulers and what they are used for. I invite students to share some of the ways they use rulers and have used them before.

 There are 2 ways that we are going to think about measuring things today: in standard units and non-standard units.

I discuss the differences between standard units (mm, cm, in) and non-standard units (a cube, paperclip, whistle, and so on) and introduce the Anchor Chart that helps students see how they can use these items to estimate length. I want to ensure students have tangible things that they can associate with different standard units (MP5).

Independent Practice

35 minutes

I have given each of you a set of tools that you will use to practice when measuring today using standard and nonstandard units. For each item, I want you to first estimate the length using one of your tools. What does it mean to estimate? When do we use estimation? Why would understanding nonstandard units help us make good estimations? Once you have your estimations, I want you to use standard units to find the actual length. You can stretch your thinking by even using non-standard units to measure other non-standard units! (MP2, MP5) We will compare what we have all discovered after some work time.


Once students have completed the measurements we discuss their individual results and what they noticed. Students should be able to discuss why understanding nonstandard units (using your knuckle or fingernail) helps to form a good estimation of length. 


5 minutes

Who can tell me why we need to use measurement? What types of jobs use measurement? Why is it important to understand which standard units are best for measuring certain objects (ie: using inches to measure a pencil, and cm to measure an eraser).

I’m impressed how you used your knowledge of number lines to make the connection to measurement! It just shows us how so much of our math is connected, and we can use what we know to learn new things. 

I have each student complete a closing activity to make a connection between units of measurement and familiar things around us (MP2). We review it as a group after students have had time to jot things down and we will return to it in upcoming days to add to it.