## SCHOOL OF FISH [DAY 2]

### DEVELOPING PLACE VALUE UNDERSTANDING

Explore efficient strategies to subtract values within 50

#### Intentionality

#### Math Talk

#### Visual Math Talk Prompt #1

#### Visual Math Talk Prompt #2

#### Visual Math Talk Prompt #3

#### Visual Math Talk Prompt #4

#### Purposeful Practice

#### Resources & Downloads

#### Educator Discussion Area

## Intentionality & Unit Overview

### Length of Unit: 5 Days

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**Intentionality…**

The purpose of the Day 2 activities is to reinforce key concepts from Day 1. Students will engage in a string of related problems through a math talk and will have an opportunity to complete purposeful practice. The math talk and purposeful practice serve to develop a deeper understanding of the following big ideas.

Some of the big ideas that may emerge today include:

- Understanding hierarchical inclusion allows for flexible composing and decomposing of numbers
- Numbers can be decomposed by separating a whole into two or more parts
- Subtraction names the missing part in terms of the whole
- Different subtraction situations will elicit different strategies
- Number relationships provide the foundation for strategies to help students remember basic facts
- Addition and subtraction are related in that addition names the parts in the whole and subtraction uses the whole to find a missing part.
- Subtraction can be used in either take away, comparison, or missing addend situations.
- Models can be used to connect concrete to abstract

*Before starting this unit, students should be familiar with:*

- Facts of 10 ( e.g., 6+4 = 10, 10-4 = 6)
- Flexibility when decomposing numbers (e.g., 13 can be decomposed into 10 and 3, but also 9 and 4, 8 and 5, etc)
- The Down and Under Ten strategy which can be explored in the Fruit Picking Unit.

## Math Talk

To practice decomposing the subtrahend, have your students work through these problems one at a time. As you present each problem, provide students with some quiet, individual think time during which they can solve the problem and show their thinking on a dry erase board, paper, etc. Then have students share their thinking either in pairs or with the whole group. **As you facilitate these conversations, it will be important to highlight how flexibly decomposing the numbers makes subtraction easier.**

The number strings are created to lead students through the process of decomposing the numbers. The first 3 prompts have 3 parts to them. The last prompt is slightly more difficult but allows students an opportunity to apply their understanding.

**String 1:**

**String 1:**

**24 – 4**

**24 – 4**

**20 – 3**

**20 – 3**

**24 – 7**

**24 – 7**

**String 2:**

**String 2:**

**32 – 2 **

**32 – 2**

**30 – 6**

**30 – 6**

**32 – 8**

**32 – 8**

**String 3:**

**String 3:**

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**Prompt 4:**

**Prompt 4:**

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## Visual Math Talk Prompt #1

## Visual Math Talk Prompt #2

## Visual Math Talk Prompt #3

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## Visual Math Talk Prompt #4

## Purposeful Practice

## Small Group Game

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## Small Group Assessment Opportunity

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## Resources & Downloads

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## Educator Discussion Area

## Explore Our 60+ Problem Based Units

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

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