ALEX Learning Activity

  

Subtraction Within 1,000 on the Number Line

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  This learning activity provided by:  
Author: Jennifer Towles
System:College/University
School:University of Montevallo
  General Activity Information  
Activity ID: 2666
Title:
Subtraction Within 1,000 on the Number Line
Digital Tool/Resource:
Subtraction Within 1,000 on the Number Line Google Slides Presentation
Web Address – URL:
Overview:

Students will use strategies based on place value to subtract in this explore activity. Students will bridge from using a concrete model to using a number line drawing when subtracting within 1,000.

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:

Students will use strategies based on place value to subtract within 1,000.

Students will use a number line drawing to show the strategy they used to subtract within 1,000.

  Strategies, Preparations and Variations  
Phase:
During/Explore/Explain
Activity:

  1. The teacher will download the presentation Subtraction Within 1,000 on the Number Line.
  2. The teacher and the students will read the learning targets together (Slide 2).
  3. The teacher will place a basket of about 1,000 objects with each group of 4 students. Each student will create a collection of 211 objects. Review efficient counting strategies (Slide 3).
  4. Check to make sure each student has 211 objects. The teacher will present the problem (Slide 4).

  • The teacher will walk around and observe how the students removed the objects. The teacher should look for three different methods of removal (all ones, tens and ones, etc.) for sharing purposes.
  • When sharing, the methods/strategies should build on one another starting with the least efficient and moving to the most efficient. The methods/strategies will be modeled on the number line. See Slide 8 for example. 
  • As the student explains their strategy to the class, the teacher will model on the blank number line. 
  • After modeling the strategies on the number line, the students will record the strategy they used to remove the objects on their personal number line recording sheet. 
  • If there are strategies used the teacher did not model, notate on the checklist/notes page. Check with those students as they are recording their strategy to determine if they need assistance. 

5. The teacher may choose to project Slides 5, 6, and 7 on a whiteboard or interactive board to model strategies or record on chart paper (Slides 5, 6, 7).

6.  The students will recreate their original collection of 211 objects (Slide 9).

7. Repeat steps 4  and 5 (Slides 11, 12, and 13) with the new problem. 

8.  Close with a discussion of subtraction strategies (Slide 15). 

Assessment Strategies:

The teacher will use the checklist/notes page to formatively assess during the activity.


Advanced Preparation:

  1. Download Subtraction Within 1,000 on the Number Line Google Slides Presentation.
  2. Gather a bucket containing close to 1,000 objects for each group of 4 students.
  3. Print one recording sheet per student.
  4. Print multiple copies of the checklist/notes page to use as a formative assessment.
  5. If the teacher prefers to model strategies on chart paper, chart paper and a chart marker will need to be gathered.
Variation Tips (optional):
 
Notes or Recommendations (optional):

2019 ALCOS

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, number line, Subtracting within 1000