Lesson 7

Workshop: Reasoning from Known Facts

Est. Class Sessions: 1
X

Mathematical Standards

3.NBT.A
Use place value understanding and properties of operations to perform multi-digit arithmetic. (3.NBT.A.2)

Standards for Mathematical Practice

MP2.
Reason quantitatively.
MP6.
Attend to precision.
MP8.
Look for and express regularity in repeated reasoning.

Students work to improve their confidence with the using-tens and thinking-addition mental math strategies for subtraction. Students practice these strategies and practice showing their reasoning with number lines, diagrams, and number sentences. Students also apply these strategies to problems with numbers larger than ten (e.g., 45 − 7).

Content in this Lesson

  • Solving subtraction problems and explaining reasoning.
  • Representing strategies for solving subtraction problems using number lines, diagrams, and number sentences [E2].
  • Reasoning from known facts to subtract: using tens, thinking addition [E5].

Daily Practice and Problems Y–Z

Y. When Is Lunch?

Z. Ways to Make 40¢

X

Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Guide
Student Activity Book

Teacher Resources

 Teacher Guide - digital

Materials for the Teacher

class number line 0–130
Unit 2 Assessment Record

Assessment in this Lesson

Assessment Expectation Assessed

Workshop: Reasoning from Known Facts
Self-Check:
Questions 1–4
Student Guide
Pages 47–48
E2.
Represent strategies for solving addition and subtraction problems using number lines, diagrams, and number sentences.
E5.
Use strategies that apply the properties of addition to solve addition and subtraction problems (e.g., making tens, using tens, thinking addition, using doubles).

Note: Focus is on using tens.

Workshop: Reasoning from Known Facts
Self-Check:
Questions 5–6
Student Guide
Page 48
E2.
Represent strategies for solving addition and subtraction problems using number lines, diagrams, and number sentences.
E5.
Use strategies that apply the properties of addition to solve addition and subtraction problems (e.g., making tens, using tens, thinking addition, using doubles).

Note: Focus is on thinking addition.

Using Subtraction Strategies
Check-In: Questions 7–9, 14, and 18
Student Activity Book
Pages 67–68, 70, and 71, respectively
E2.
Represent strategies for solving addition and subtraction problems using number lines, diagrams, and number sentences.