Lesson 1

Invented Strategies

Est. Class Sessions: 2–3
X

Mathematical Standards

1.OA.A
Represent and solve problems involving addition and subtraction. (1.OA.A.1, 1.OA.A.2)
1.OA.B
Understand and apply properties of operations and the relationship between addition and subtraction. (1.OA.B.3, 1.OA.B.4)
1.OA.C
Add and subtract within 20. (1.OA.C.6)
1.OA.D
Work with addition and subtraction equations. (1.OA.D.8)

Standards for Mathematical Practice

MP1.
Make sense of problems and
persevere in solving them.
MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.

During a strategy session, students review strategies they used in previous lessons, develop more strategies for sums greater than 10, and record them on an invented strategies chart. Then they solve problems with larger sums and describe the strategies and tools they use.

Content in this Lesson

  • Representing addition and subtraction situations using drawings, diagrams, counters, number sentences, number lines, or ten frames [E2].
  • Solving word problems (e.g., join, separate/take away, part-whole, compare) involving two whole numbers whose sum is between 10 and 20 [E3].
  • Using mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten) to solve addition with sums between 10 and 20 and the related subtraction problems [E5].
  • Using strategies that apply the properties of addition (e.g., turn-around, compose and decompose numbers) to solve addition and subtraction problems [E6].
  • Finding the unknown whole number in an addition or subtraction equation relating three whole numbers [E7].
  • Knowing what is important to solve a problem [MPE1].
  • Finding strategies to solve problems [MPE2].
  • Checking for reasonableness [MPE3].
  • Showing or telling how to solve problems [MPE5].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

20 connecting cubes
desk number line (0–40)

Materials for the Teacher

Display of Two Ten Frames (Teacher Guide)
Prepared set of the Addition Cards for Larger Sums 1–3 Masters (Teacher Guide)
Display of Addition Strategies Menu for Small Numbers (Student Activity Book) Reference
Display of Math Practices (Student Activity Book) Reference
Display of Use Strategies to Solve Problems (Student Activity Book) Pages 361–362
Unit 12 Assessment Record
Math Facts Class Record
chart paper

Materials Preparation

Prepare Chart with Sample Problem. Write the following problem on a chart or other display:

Grace and Jerome were jumping rope to raise money for the neighborhood animal shelter. Grace jumped for 9 minutes and then Jerome jumped for 7 minutes. How many minutes did they jump altogether?

Prepare Addition Cards. Copy and cut out one set of addition cards for each student pair using the Addition Cards for Larger Sums 1–3 Masters. If possible, use heavy paper or card stock to make the cards. Clip each set together. For demonstration purposes, copy one set on colored paper and cut apart cards.

Prepare Sorting Mats. For display, use the Sorting Mat for Larger Sums Master to draw a Sorting Mat on chart paper. See Figure 1. Each student pair will also need a sorting mat. Use the Sorting Mat for Larger Sums Master to make a sorting mat on 11 x 17–inch paper. To copy the mat from an 8.5 x 11–inch paper to 11 x 17–inch paper increase the copy ratio to 130%. Sorting mats can also be drawn on chart paper.

Prepare Ten Frames, Number Lines, and 100 Charts. If you have not done so already, make copies of the Ten Frames and Number Line Master and the 100 Chart Master back-to-back on heavy card stock for each student. Provide students with one set to use in class and another to use at home. Laminating makes these tools more durable.



Figure 1: A sorting mat on chart paper

Assessment in this Lesson

ASSESSMENT EXPECTATION ASSESSED MATH PRACTICES EXPECTATION ASSESSED
Think about Strategies for Solving Problems
with Feedback Box
Student Activity Book
Pages 363–364
E2.
Represent addition and subtraction situations using stories, drawings, diagrams, counters, number sentences, number lines, or ten frames.
E3.
Solve word problems (e.g., join, separate/take away, part-whole, compare) involving two whole numbers whose sum is between 10 and 20.
E5.
Use mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten) to solve addition problems with sums between 10 and 20 and the related subtraction problems.
E6.
Use strategies that apply the properties of addition (e.g., turn-around, compose and decompose numbers) to solve addition and subtraction problems.
E7.
Find the unknown whole number in an addition or subtraction equation relating three whole numbers.
MPE1.
Know the problem. I read the problem carefully. I know the questions to answer and what information is important.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE3.
Check for reasonableness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
DPP Item A
Addition Flash Cards:
Group A
Teacher Guide - digital
E8.
Demonstrate fluency with the addition facts in Group A (0 + 1, 1 + 1, 2 + 1, 3 + 1, 0 + 2, 2 + 2, 3 + 2, 4 + 2).
DPP Item B
Fact Families:
Group A
Teacher Guide - digital
E9.
Determine the unknown number in an addition or subtraction sentence relating three whole numbers for the facts in Group A.

Vocabulary in this Lesson