# Estimating & Measuring Weight

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## Objective

SWBAT estimate and measure the weight of grocery store products.

#### Big Idea

In order to further develop students' understanding of measurement units, it is important to provide students with opportunities to estimate and measure the weight of items.

## Opening

15 minutes

To connect this lesson with yesterday's lesson, Day 6: What's an Ounce?, I began by asking: What did learn about an ounce yesterday? Students responded, "That an ounce would be used to weigh an apple." "One clay ball equals an ounce." "It takes 16 ounces or clay balls to get to a pound." Good! I'm glad you mentioned a pound! I held up the examples of 1 ounce (one clay ball) and 16 ounces (16 clay balls): One Ounce vs One PoundDoes everyone remember yesterday when we were talking about the two systems of measurement: Metric and US Customary? We talked about how grams and ounces are not equal, but you would use both grams and ounces to weigh one apple. What about a bunch of apples? What metric unit would you use? "A kilogram!" What customary unit would you use to weigh a bunch of apples? "A pound!" One student asked, "But how many pounds are in a kilogram?" I asked him to look this up on the internet!

At this point, the student looking up the conversion between pounds and kilograms we ready to share what he found: Kilograms to Pounds Conversion. He shared his findings with the rest of the class. Regularly using computers in the classroom supports Math Practice 5: Use appropriate tools (including technological tools) strategically.

## Teacher Demonstration

20 minutes

Students were ready to hear about the Grocery Mart drawing on the board! I simply projected clipart from my computer and traced around it, hoping to help make this lesson come alive! Again, by applying math to an everyday scenario, students learn the importance of math in real life (Math Practice 4).

## Student Practice

30 minutes

Students were more than ready to begin investigating on their own! In my classroom, I always have students' desks placed in groups to make collaborative learning practical and easy to implement. I regularly ask students to work in groups to support Math Practice 3: Construct viable arguments and critique the reasoning of others. To start students off, I asked my weekly-assigned team leaders to grab a product from the board and begin!

During this time, I walked from group to group to observe students learning. My goal was to reinforce key concepts and to identify student misconceptions. I tried to provide on-the-spot interventions through questioning and modeling.

In this video, you'll see students excitedly revealing the actual weight of a Hersey's bar: Revealing Actual Weight. Other students used one of the digital scales throughout the room to check the weight.

In this video, Measuring Products, students compare their estimated weights to the actual weight. I encouraged the students to grab a few green one-ounce balls from yesterday's lesson to connect new knowledge with prior learning and to help students apply their understanding of a ounce to this activity. Later in the activity, I reconnect with this group and find that they have gathered three one ounce balls to help with estimating: Comparing One Ounce Balls. I loved watching how eager the students were to place their hands on these products!

Here, I used Questioning to push this student's thinking. Even this short conference was somewhat challenging as she was so focused on the activity at hand. She was more interested in interacting with these products than talking to me!

## Closing

10 minutes

To bring closure to the lesson, I first asked students to put all of the products back and sit down in their seats as I counted down from 10. I then asked students to turn and talk about two questions:

1. Were you surprised by any of the products' weights?