Task Teacher Guide
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In This Purposeful Practice…
Students will demonstrate the concepts and skills that they have developed through this context and learning experience.
Intentionality…
The purpose of this assessment is for students to demonstrate their understanding of the following big ideas.
- The action of removal is represented by subtraction.
- Removal problems can be solved by addition or subtraction.
- Unitizing 10 single cookies into one group of 10 cookies.
- When adding two digit numbers, regrouping 11-19 single cookies in the partial sum into a group of 10 and some leftover singles.
- Addition and subtraction problems within 100 can be solved using strategies along a developmental continuum of counting all, counting on/back, and using place value strategies.
- When students are using place value strategies to solve addition and subtraction problems within 100, they are using their understanding of tens and ones and decomposition to accurately, flexibly, and efficiently solve problems. See the Student Approaches section in this guide for examples.
The independent assessment will allow students to demonstrate concepts and skills related to the following learning goals:
- I will write an equation that represents the story situation.
- I will use a model such as a diagram or equations to show how I solved the problem.
- I will accurately solve subtraction problems using appropriate strategies.
- I will write a subtraction story that matches a given equation.
- Students might write and/or model their answers independently. Students can also be interviewed by their teacher.
An alternative assessment opportunity should be offered if this tool will not successfully capture what the student knows, understands or can do.
Math Talk
Overview of This Math Talk
In order to encourage the place value strategy of keeping the first number (the minuend) whole and subtracting the second number (the subtrahend) in parts, work through this number string with your class one problem at a time. As you present a problem, provide students with some individual think time to mentally solve it. When students share their response and reasoning, consider modeling their thinking on an open number line in order to make it visible to their classmates.
Note: Watch How to Facilitate the Day 4 Math Talk for a model of what this lesson looks and sounds like.
The first four problems go together. After solving the first three problems, some students might realize they already have the answer when you show 67-39. The three helper problems are helping them to learn how to subtract by parts using place value strategies.
The next four problems go together in another set to support student understanding of place value strategies in subtraction situations. First, some tens are taken away in 73-40. Then, to get us to a landmark (multiple of ten number) some of the ones are taken away in 33-3. Then, the rest of the ones are taken away in 30-5. As with the first set, some students may realize that they already have the answer to the final problem 73-48 when it is presented.
The final two problems, 82-27 and 76-48, are opportunities to practice using place value strategies without the support of helper problems.
67 – 30
37 – 7
30 – 2
67 – 39
73 – 40
33 – 3
30 – 5
73 – 48
82 – 27
76 – 48
Assessment Considerations…
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Assessment Task: Addition and Subtraction within 100
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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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Resources and Downloads
Lesson Tip Sheet
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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.
Number Talk Prompt #1
67 – 30
Number Talk Prompt #2
37 – 7
Number Talk Prompt #3
30 – 2
Number Talk Prompt #4
67 – 39
Number Talk Prompt #5
73 – 40
Number Talk Prompt #6
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Number Talk Prompt #7
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Number Talk Prompt #8
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Number Talk Prompt #9
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Number Talk Prompt #10
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Option #1
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Option #2
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Option #3
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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