## ZEN ZEBRAS [DAY 3]

### ADDITION STRATEGY: BREAK APART ONE ADDEND

Dive into this 5-Day Problem Based Math Unit which focused on the efficient strategy of breaking apart one addend to add values within 50

## Intentionality & Unit Overview

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Students will solve a subtraction question using the takeaway strategy of decomposing the subtrahend.Â

## Intentionalityâ€¦

Students will solve an addition question using the addition strategy of Breaking Apart one number.Â

Some of the big ideas that may emerge through this task 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
• Addition names the whole in terms of the partsÂ
• Different addition situations will elicit different strategiesÂ
• Number relationships provide the foundation for strategies to help students remember basic facts
• Models can be used to connect concrete to abstractÂ

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 Up and Over Ten strategy which can be explored in the Bowling Pins Unit.

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

Show students the following video:

What do you notice?
What do you wonder?

Give students about 30-60 seconds to do a rapid write on a piece of paper or silent individual think time.

Replaying the video can be helpful here if appropriate.Â

Then, ask students to pair share with their neighbours for another 60 seconds.

Finally, allow students to individually share with the entire group. Be sure to write down these noticings and wonderings on the blackboard/whiteboard, chart paper, or some other way that is visible to all. This helps students to see the thinking of their classmates andÂ  ensures each student that their voice is acknowledged and appreciated. Adding student names or initials next to their notice/wonder is one way to acknowledge their participation and can motivate others to join in.

Some noticings and wonderings that may come up:

• I notice that there are zebras eatingÂ
• I notice that the zebras looked scared
• I wonder if the zebra can see the lion
• I wonder if there are more than one lion
• I wonder if the zebras are going to run away
• And many more

## Crafting A Productive Struggle: Prompt

Since weâ€™ve already invested time to set the context for this problem and student curiosity is already sparked, we have them in a perfect spot to help push their thinking further and fuel sense making. Here we are asking students to envision a solution path. By considering what information will be needed and how it can be used to solve the problem, students are being asked to make sense of the problem and reason abstractly and quantitatively. By not simply providing this information, we are inducing students to engage more deeply with the problem and think about all of its parts, known and unknown, before they begin crunching the numbers.Â

## While Students Are Productively Struggling…

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## Student Approach #1: Counting All with a Drawing

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## Student Approach #2: Counting on using tallies to keep track

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## Student Approach #3: Breaking Apart both numbers by place value then adding

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## Student Approach #4: Breaking Apart one number efficiently (on an open number line)

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## Student Approach #5: Algorithm

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## Reveal

Show students the following reveal video: There are two different options for the reveal to reflect possible ways that students will break apart the addend. Some students may choose to add to a decade number first by decomposing the 6 in this case. On the other hand, a student may decompose the 26 by adding the tens first. Regardless, students are encouraged to decompose the number into logical pieces for the question. It would not be helpful for students to decompose 26 into 20+3+3, instead encourage students to decompose to get to a decade number.

## Consolidation

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## Reflect and Consolidation Prompts

Provide students an opportunity to reflect on their learning by offering these consolidation prompts to be completed independently and then discussed as a class.

### Consolidation Prompt #1:

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### Consolidation Prompt #2:

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We suggest collecting this reflection as an additional opportunity to engage in the formative assessment process to inform next steps for individual students as well as how the whole class will proceed.

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## Educator Discussion Area

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