Mary Ellen Kanthack BROOKWOOD MIDDLE, GENOA CITY, WI
4th Grade Math : Unit #2 - Metric Measurement : Lesson #4

Building a Meter: Comparing units.

Objective: SWBAT show and explain the units within a meter (mm, cm, dm) and compare their relationship to each other.
Standards: 4.OA.B.4 4.MD.A.1 4.MD.A.2 4.MD.A.3 MP4 MP5
Subject(s): Math
60 minutes
1 Warm Up: Factor Pair Quiz - 10 minutes

In order to be sure that students are mastering the standard 4.OA.B.1 which requires that they find all factor pairs from 1-100, I am keeping a log on a Google Doc. I am keeping track of their progress and quizzing them once a week on various products. I keep track of which products I am testing by crossing them off on a 100's chart. Students practice finding factor pairs during the rest of the week to hone their skills for this quiz. Today I chose 10 products, 7,17,27,37,47,57,67,77,87,97. The students list factor pairs starting with 1x the product, etc until they think all are found. In order to be excluded from the practice during the week, students must achieve 100 % on this quiz. I gave them about 10 minutes to complete. I collect them and record scores on a spreadsheet. I am looking for fluency in facts, and strategies in finding the factor pairs. I have dismissed one student who has achieved 100% on every test thus far, demonstrating that she has mastered the standard.

 

2 Building a Meter - 20 minutes

Build a Meter Guide.pdf

Paper meter resource

Rationale: The idea behind this activity helps students really understand how many centimeters and decimeters make up a meter in a very hands on way.

Using centimeter cubes ( the unit cubes from a place value block set) and meter sticks, my partnered students began to start to lay the little cubes next to the meter stick. I asked them to count the little cubes after they were done lining them up.Building that meter shows them counting. Next, they laid the rods ( from the same set) down to measure in decimeters.Build a Meter Guide.pdf I had told them that a decimeter was about the size of the hand from where fingers start, through the palm and down to where the wrist starts. I noticed many had laid the rod in their hand and examined that idea for a few minutes before they placed them along the meter.

Through this building, they could count and see exactly how a meter is built upon powers of 10. I asked them to count the amount of millimeters they could see in the cube. This "math play" took up more time than I expected because it is a tedious process to lay all the cubes down and then count. But, I think it is one of the best ways to develop the concept of the amount; what centimeters look like when there are one hundred all in a row. The rods show that that there are 10 cubes and they easily can see how those rods are made up of ten cubes. These familiar place value tools have now taken on a new meaning.

 

3 Informal assessement of understanding - 10 minutes

Assessing Understanding: In order for me to get a clear picture of their understanding, I asked them to practice explaining what they had learned by telling me how many cubes and rods were in the meter and relating back to mm, cm & decimeters. I told them to practice well enough that they could video it in less than 50 seconds. Here are a few samples of their work in explaining what they understood from this hands on experience. Every student was able to explain each unit very well.In Explaining his learning, this young man shows he has a grip on what a meter is built out of. Working hard to explain was a very clear sample of how a meter is put together. These two practiced a lot to get it accurately done. Explaining how a meter is put together shows his thinking well. In all three movies, we can see the thinking process as they have to explain to one another and keep one another in check. This lesson is just too fun!

Supporting understanding through guided discovery.
Developing a Conceptual Understanding

I chose to introduce metric measurement using meters first because it was the easiest to develop their conceptual understanding that the metric system is based on ten. The meter is a number line and so this concept is visually easy to understand. From this point on, they can move forward in understanding that the other base units are based on this number line concept of ten. This is the first lesson in a series of three discovery lessons. Math Practice Standards 4 & 5 are practiced in this lesson clearly by them as they manipulate tools, read the meter stick or tape and then explain their model in their assessment video. We are also mastering the portion of the standard that expects that students have understanding of relativity to the units. They can see the size of the centimeter and decimeter ( a harder concept) through the cubes and rods. It is a really fun lesson to start them off solidly in understanding the metric system.