GUMMY WORMS [DAY 3]
SUBTRACTION
Uncover the various subtraction structures including removal, conparison, missing, addend, and missing subtrahend.
Intentionality
Math Talk
Spark Curiosity
Fuel Sensemaking
During Moves
Student Approaches
Consolidation
Purposeful Practice
Resources & Downloads
Educator Discussion Area
Intentionality & Unit Overview
Length of Unit: 5 Days
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Students will explore a second subtraction structure: difference (or comparison).
Intentionality…
The purpose of the Day 3 activities is to reinforce key concepts from Day 1 and to explore a new subtraction structure. Students will engage in a math talk, investigate a new task and independently complete purposeful practice. Today’s learning serves to develop a deeper understanding of the following big ideas.
- Relationships between addition & subtraction.
- One-to-one correspondence.
- One structure of subtraction is “removal”.
- Measured and unmeasured comparison can be used to describe the relationship between two quantities.
- One structure of subtraction is comparison (or difference).
Math Talk
Related String of Problems
Through the following string or related problems, students might be encouraged to use the “taking jumps of ten” strategy, while others might begin exploring “counting on”. Some students might see the opportunity to use the strategy “one more, one less” when the subtrahend is one larger than the previous problem.
Consider recording student strategies on a concrete number line or number path. Two different structures of subtraction (separating and comparison) may emerge during this string depending on how students communicate their thinking.
13 – 10
13 – 9
13 – 11
18 – 10
18 – 11
18 – 13
Spark Curiosity
Building On The Context Through Storytelling
Remind students of the context developed on Day 1.
For today’s task, you might consider bringing in two jars of gummy worms, or explaining the situation orally.
As you know, I have a jar that contains 25 gummy worms. When I went home last night, I saw a second jar on the counter…
[At this point, you might consider displaying both jars and proceed to ask the question]
…which jar do you think has more gummy worms?
Give students an opportunity to turn and talk and then ask a few students to share out. Encourage students to defend their answer. This conversation will lead students to the big idea of using unmeasured comparison to describe the relationship between two quantities.
Fuel Sense-making
Crafting A Productive Struggle: Prompt
Tell students that you want to be more precise, you want to know with certainty which jar has more gummy worms and to be more exact, how many more.
Consider counting the number of gummy worms in each jar together, and then sending students off to determine how many more gummy worms are in the jar with the greater quantity.
Then you can share one of the following prompt options for your students:
Prompt Option #1:
There are 25 gummy worms in the first jar and 19 gummy worms in the second jar. How many more gummy worms are in the jar with the greater quantity?
Or…
Prompt Option #2:
There are 25 gummy worms in the first jar and 19 gummy worms in the second jar. How many less gummy worms are in the jar with the smaller quantity?
Facilitator Notes
In this task, students will have an opportunity to reason through a subtraction scenario. This particular problem is an example of the “comparison” subtraction structure, also referred to as “difference”. This task will allow students to apply a variety of strategies and models, while developing a deeper understanding of big ideas, specifically the following:
- Measured and unmeasured comparison can be used to describe the relationship between two quantities.
- One structure of subtraction is comparison (or difference).
During Moves
While Students Are Productively Struggling…
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Student Approaches
Student Approach #1: Pictorial & Counting On
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Student Approach #2: Concrete & Counting By 1s
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Student Approach #3: Mental Math With Friendly Facts
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Consolidation
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Purposeful Practice
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Resources & Downloads
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Printable Lesson Plan PDF
Videos, Images & Media Files
Apple Keynote Presentation
Powerpoint Presentation
Printable Consolidation Prompts
Educator Discussion Area
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