Lesson 2

An Addition Seminar

Est. Class Sessions: 2–3
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Mathematical Standards

2.NBT.A
Understand place value. (2.NBT.A.1, 2.NBT.A.2)
2.NBT.B
Use place value understanding and properties of operations to add and subtract. (2.NBT.B.6, 2.NBT.B.7, 2.NBT.B.8, 2.NBT.B.9)
2.MD.B
Relate addition and subtraction to length (2.MD.B.6)
2.OA.A
Represent and solve problems involving addition and subtraction. (2.OA.A.1)

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.
MP6.
Attend to precision.

Students develop strategies for solving addition problems with multidigit numbers. As a class, students share strategies and record them on a chart.

Content in this Lesson

  • Using and applying place value concepts to make connections among representations of numbers [E1].
  • Representing addition problems using base-ten pieces, number lines, and number sentences [E2].
  • Adding two-digit numbers using mental math strategies (e.g., composing and decomposing numbers, counting on) using the 200 Chart and number lines [E3].
  • Knowing what information is important in a problem [MPE1].
  • Finding addition strategies to solve problems [MPE2].
  • 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 Student Pairs

base-ten pieces (21 bits, 20 skinnies)
connecting cubes
desk number line (0–100)

Materials for the Teacher

Display of I Just Used My Head Master (Teacher Guide)
Display of 200 Chart (Student Activity Book) Reference
Unit 7 Assessment Record
class number line (0–130) or prepared Number Line Display Masters (Teacher Guide). See Materials Preparation.
chart paper

Materials Preparation

Prepare Number Line Display. If you did not prepare a number line in Unit 2 Lesson 1 that students can easily see and touch, prepare the Number Line Display Masters. This version can be assembled, laminated, and displayed on the board or on a bulletin board. It is small enough that it could be moved when it is not needed.

Assessment in this Lesson

ASSESSMENT EXPECTATION ASSESSED MATH PRACTICES EXPECTATION ASSESSED
How Did They Do It
with Feedback Box
Student Activity Book
Pages 329–330
E1.
Use and apply place value concepts to make connections among representations of numbers to the thousands using base-ten pieces, number lines, expanded form, and standard form.
E2.
Represent addition problems using base-ten pieces, number lines, and number sentences.
E3.
Add two-digit and three-digit numbers using mental math strategies (e.g., composing and decomposing numbers, counting on) using the 200 Chart, base-ten pieces, and number lines.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.

Vocabulary in this Lesson