## Task Teacher Guide

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### In This Task…

In today’s piggy bank scenario, we will compare the value of coins in two separate piggy banks relative to the cost of one pack of Pokemon cards using comparison subtraction. As an additional level of complexity, we will have to adjust the value of one piggy bank due to an I.O.U. (i.e.: “I owe you”) situation.

### Intentionality…

In this task, students will compare decimal values using comparison subtraction. An I.O.U. (i.e.: “I owe you”) will be added to one piggy bank to introduce the idea of adding a negative value. Students will once again be encouraged to compare the values using a linear model. This model will once again expose the relationship between decimals and fractions as students are required to partition the linear model.

**All tasks within this unit are intended to be completed without the use of a calculator to support reasoning and thinking.**

Some of the * big ideas* that may emerge through this task include:

- Fractions can be represented in a variety of ways;
- Fractions (and their decimal representation) represent values relative to a whole (for example, one whole dollar);
- Quantities represented as a decimal are fractions limited to base ten denominators (i.e.: tenths, hundredths, thousandths, etc.);
- Standard representation of coin values are expressed as decimal hundredths;
- Subtraction can mean difference and is used to compare two quantities;
- Removal subtraction of a positive value or adding the negative of that same value has the same result, i.e., 6 – 2 = 6 + (-2).

## Spark

### What Do You Notice? What Do You Wonder?

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### Estimation: Prompt

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### While Students Are Estimating…

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### Estimation Reveal

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## Sense Making

### Crafting A Productive Struggle: Prompt

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## During Moves

### While Students Are Productively Struggling…

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### Student Approach #1: Bar Model w/ Partial Sums Over Addition

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### Student Approach #2: Number Line w/ Partial Sums Over Subtraction

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## Next Moves

### Consolidation

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### Reveal

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### Reflect

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## Resources and Downloads

## Lesson Tip Sheet

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## Videos & Images

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## Keynote Slides

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## PowerPoint Slides

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## Printable Handout

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## Explore The Entire Unit of Study

This Make Math Moments Task was designed to spark curiosity for a multi-day unit of study with built in purposeful practice, and extensions to elicit and emerge mathematical models and strategies.

Click the links at the top of this task to head to the other related lessons created for this unit of study.

### What Do You Notice? What Do You Wonder?

### Spark Image

### Estimation: Prompt

*How much money does Youssef have to spend?*

*How much money does William have to spend?*

*Make an estimate for each.*

*Use an equation to represent Youssef’s deposits and another to represent William’s deposits.*

### Estimation: Image

### Estimate: Canadian Reveal Video

### Estimate: Canadian Reveal Image

### Estimate: United States Reveal Video

### Estimate: United States Reveal Image

### Consolidation Prompt #1

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### Consolidation Prompt #2

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**Download Editable/Printable Handout**

Become a member to access purposeful practice to display via your projector/TV, download the PDF to upload to your LMS and/or print for students to have a physical copy