BARNYARD [DAY 4]
Subtraction: Counting Back and Adding Up
Investigate early subtraction strategies through counting back and adding up to find the difference.
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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Students will continue exploring subtraction and using a strategy that is flexible based on the numbers presented in the question. The visual math talk and purposeful practice that could be used in small groups and for an assessment opportunity.
The purpose of the Day 4 activities is to reinforce key concepts from Day 3. Students will engage in 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.
- Subtraction names the missing part in terms of the whole
- Counting back is efficient when the count back is small
- Adding up to find the difference is efficient with the subtrahend is close in value to the minuend
- 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.
Math Talk
The purpose of today’s math talk is to expose students to questions when it would be most efficient to use the strategy of “counting back” and questions when it would be most efficient to use the strategy of “adding up”. The string will start with counting back which is the strategy that students are typically more comfortable with followed by questions with purposefully chosen numbers that would be much easier if added up instead. This will present the opportunity for a discussion about why the numbers in a question will help decipher the proper strategy to choose.
Visual Math Talk Prompt #1
As students are determining the other part, observe which strategies they are using.
- Are they using their fingers to track?
- Are students holding up their fingers and creating their own “part whole”, by putting down 2 fingers and counting the rest?
- Are they counting 2 back from 9?
- Are they starting at 2 and counting forward to 9?
As part of the consolidation for this prompt, discuss how it is more efficient to count back from 9 because it is only 2 away. Try to use the word efficient rather than faster. We don’t want to encourage speed when we are solving a math problem but rather efficiency in getting to the answer with the least amount of steps.
Visual Math Talk Prompt #2
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Visual Math Talk Prompt #3
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Visual Math Talk Prompt #4
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Purposeful Practice
While Students Are Practicing…
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Purposeful Practice: Game
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Small Group Assessment Opportunity:
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Resources & Downloads
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Educator Discussion Area
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