ALEX Learning Activity

  

Subtraction With Larger Numbers

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  This learning activity provided by:  
Author: Jennifer Towles
System:College/University
School:University of Montevallo
  General Activity Information  
Activity ID: 2664
Title:
Subtraction With Larger Numbers
Digital Tool/Resource:
Google Slides Presentation: Subtraction with Larger Numbers
Web Address – URL:
Overview:

In this before activity, students will engage in a number talk to link strategies used with numbers within 100 to numbers within 1,000. The number talk uses numbers under 120.

This activity was created as a result of the ALEX Resource Development Summit.

  Associated Standards and Objectives  
Content Standard(s):
Mathematics
MA2019 (2019)
Grade: 2
12. Add and subtract within 1000 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.

a. Explain that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
Unpacked Content
Evidence Of Student Attainment:
Students:
  • add and subtract within 1000.
  • explain their reasoning using concrete models or drawings, or using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
  • relate the strategy used to a written method (symbolic and numeric recording of the steps used).
Teacher Vocabulary:
  • Compose
  • Decompose
Knowledge:
Students know:
  • how to count to 1,000.
  • how to identify hundreds, tens, and ones.
  • how to compose numbers.
  • how to decompose two digit numbers.
  • how to record strategies for solving addition and subtraction problems.
Skills:
Students are able to:
  • add and subtract within 1000.
  • model addition problems using visual models.
  • record strategies for solving addition problems.
  • communicate the relationship between models and symbolic (numeric) representations.
Understanding:
Students understand that:
  • relationships between models of addition/subtraction problems and written strategies of those models can be used to justify solutions.
Diverse Learning Needs:
Essential Skills:
Learning Objectives:
M.2.12.1: Define regrouping, total, sum, difference and solve.
M.2.12.2: Add and subtract two two-digit numbers with and without regrouping.
M.2.12.3: Determine the value of the number in the ones, tens, hundreds and thousands place using concrete models or drawings and strategies based on place value.
M.2.12.4: Match the number in the ones, tens, hundreds and thousands position to a pictorial representation or manipulative of the value.
M.2.12.5: Model written method for recording horizontal and vertical addition and subtraction problems.
M.2.12.6: Represent two- and three-digit numbers with multiple models.
Examples: models—base ten blocks, number lines, linking cubes, straw bundles.
M.2.12.7: Recall single-digit addition and subtraction facts.
M.2.12.8: Add and subtract within 20, e.g., by using objects or drawings to represent the problem.

Prior Knowledge Skills:
  • Notice same/different and some/all.
  • Recognize numerals from 1-50.
  • Add one to a set of objects (up to 10 objects).
  • Given small groups of objects, create larger groups by combining the small groups.
  • Understand ten and 1 (ten 1's =10).
  • Put together two small groups of objects to create a larger group.
  • Subtract one from a set of objects (up to 10 objects).
  • Given a group of objects (20 or less), divide the group into smaller groups in various ways.
  • Take away objects from a large group to create two smaller groups.
  • Understand number words.
  • Establish one-to-one correspondence between numbers and objects when given a picture a drawing or objects.
  • Rote count to 10.
  • Understand amount words, such as more, less, and another.
  • Begin to understand that parts of an object can make a whole.

Alabama Alternate Achievement Standards
AAS Standard:
M.AAS.2.10 Using vocalization, sign language, augmentative communication, or assistive technology, identify the meaning of the + sign (add, plus, put together) and the sign (subtract, take away, take from) and the = sign (equal, the same as); compose and decompose numbers up to 20 using objects, pictures, drawings, or numbers.


Learning Objectives:

The students will use strategies based on place value and the properties of operations to subtract within 1000.

  Strategies, Preparations and Variations  
Phase:
Before/Engage
Activity:

  1. The teacher will download Google Slide Presentation: Subtraction with Larger Numbers.

  2. Young students do not always understand that the strategies they use with smaller numbers work with bigger numbers. The numbers chosen in this activity are designed to encourage students to decompose the subtrahend in order to subtract in friendly parts.

  3. The teacher and the students will read the learning targets together (Slide 2).

  4. The teacher will gather the students together in a central location where the students can view a whiteboard, interactive board, or chart paper. The teacher will pose the following problems one at a time: 16 - 7 =? 56 - 7 =?  and 116 - 7=?. The teacher and the students will follow the steps below: The teacher will pose a problem. The students will solve the problem in their head or mentally. When the students have an answer, they will place a thumbs up against their chests. The teacher will call on three students to share their answers. The teacher will record the students’ answers on the board. The teacher will call on three students to share how they solved the problem. The teacher will record their strategy on the board (Slide 3).

  5. The teacher presents 16 - 7 = ? to the class. The teacher is ultimately looking for students to decompose 7 into 6 and 1.

    16 - (6+1) = ? or 16 - 6 - 1 = ?

    16 - 6 = 10

    10 - 1 = 9

    The teacher should model the students' strategies on a number line. The teacher may record students’ strategies in the white area on the slide, on chart paper, or on notebook paper under a document camera. Use the checklist/notes to record the strategies used (Slide 4).

  6. The teacher presents 56 - 7 = ? to the class.The teacher is ultimately looking for students to decompose 7 into 6 and 1.

    56 - (6+1) = ? or 56 - 6 - 1 =?

    56 - 6 = 50

    50 - 1 = 49

    The teacher should model the students' strategies on a number line. The teacher may record students’ strategies in the white area on the slide, on chart paper, or on notebook paper under a document camera. Use the checklist/notes to record the strategies used (Slide 5).

  7. The teacher presents 116 - 7 = ? to the class.The teacher is ultimately looking for students to decompose 7 into 6 and 1.

    116 - (6+1) = ? or 116 - 6 - 1 = ?

    116 - 6 = 110

    110 - 1 = 109

    The teacher should model the students' strategies on a number line. The teacher may record students’ strategies in the white area on the slide, on chart paper, or on notebook paper under a document camera. Use the checklist/notes to record the strategies used (Slide 6).

  8. The teacher will review the strategies used with all three problems using the guiding questions on the slide. If no student decomposed 7 into 6 and 1. The teacher will need to ask, “How could decomposing 7 into 6 and 1 make 7 easier to subtract in this problem?” (Slide 7).

Assessment Strategies:

The teacher will use the checklist/notes to record the strategies used.


Advanced Preparation:

  1. The teacher will download Google Slide Presentation: Subtraction with Larger Numbers.
  2. If the teacher plans to use chart paper and a chart marker, those items will need to be gathered.
  3. Print the checklist/notes to record the strategies used.
Variation Tips (optional):
 
Notes or Recommendations (optional):

ALCOS 2019

ALCOS 2.12). Add and subtract within 1000 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.

a. Explain that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.

  Keywords and Search Tags  
Keywords and Search Tags: decomposing numbers, subtracting in parts, subtracting within 100