Objective
Relate subtraction with place value drawings to the standard algorithm.
Student-Facing
I can record my subtraction thinking vertically.
Common Core Standards
Core Standards
The core standards covered in this lesson
2.NBT.B.5— Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Number and Operations in Base Ten
2.NBT.B.5— Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
2.NBT.B.9— Explain why addition and subtraction strategies work, using place value and the properties of operations.Explanations may be supported by drawings or objects.
Number and Operations in Base Ten
2.NBT.B.9— Explain why addition and subtraction strategies work, using place value and the properties of operations.Explanations may be supported by drawings or objects.
Foundational Standards
The foundational standards covered in this lesson
1.NBT.C.4
Number and Operations in Base Ten
1.NBT.C.4— Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
1.NBT.C.5
Number and Operations in Base Ten
1.NBT.C.5— Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
1.NBT.C.6
Number and Operations in Base Ten
1.NBT.C.6— Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
See AlsoLesson 13 | Adding and Subtracting Within 1,000 | 2nd Grade Mathematics | Free Lesson PlanRegression and Predictions. Exercises 13-28 use the same data sets as Exercises 13-28 in Section 10-1. (a) Find the regression equation, letting the first variable be the predictor (x) variable. (b) Find the indicated predicted value by following the predLesson 13 | Measurement | 2nd Grade Mathematics | Free Lesson PlanProblem 113 Graph the solution set, and writ... [FREE SOLUTION]1.OA.B.3
Operations and Algebraic Thinking
1.OA.B.3— Apply properties of operations as strategies to add and subtract.Students need not use formal terms for these properties.To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.)
1.OA.B.4
Operations and Algebraic Thinking
1.OA.B.4— Understand subtraction as an unknown-addend problem.For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
Criteria for Success
The essential concepts students need to demonstrate or understand to achieve the lesson objective
- Understand how a subtraction problem can be represented using numbers stacked vertically, aligned by place value as in a place value chart.
- Represent a subtraction problem in a vertical model with numbers aligned by place value.
Tips for Teachers
Suggestions for teachers to help them teach this lesson
- Since this is the first time students will solve subtraction situations with two-digit numbers within 100 using the standard algorithm there are no situations where students need to decompose a ten to subtract in this lesson.
- In directions, we direct students to record their thinking vertically. Some people may refer to this as stacking where, when using the standard algorithm, students show their mathematical thinking by recording the numbers on top of each other aligned by place value.
- As a reminder, students do not need to know that the strategy is called the standard algorithm and are not expected to be fluent with this method until fourth grade (4.NBT.B.4); therefore, students' work should be supported with place value drawings as they internalize and make sense of the process.
Warm Up
5-10 minutes
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Anchor Tasks
Tasks designed to teach criteria for success of the lesson, and guidance to help draw out student understanding
15-25 minutes
Problem 1
Trevor showed his subtraction with the place value drawing shown below.
a.What subtraction problem was Trevor solving? Write an equation to represent his work.
b.How could you represent this problem and solution vertically, similar to how it is modeled in the place value chart?
Purpose
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Problem 2
Model subtracting using a place value chart. Record your thinking vertically.
a.66 - 25 =______
b.58 - 34 =______
Purpose
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Facilitation Guidance
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Problem Set
15-20 minutes
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Target Task
A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved
5-10 minutes
Model subtracting using a place value chart. Record your thinking vertically.
a.75 - 22 =
b.68 - 36 =
Student Response
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Additional Practice
Daily Word Problems, Warm Ups, and Center Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.
Word Problems and Fluency Activities
Word Problems and Fluency Activities
Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.
Lesson 12
Lesson 14
