Curriculum  /  Math  /  2nd Grade  /  Unit 2: Adding and Subtracting Within 100  /  Lesson 4

Adding and Subtracting Within 100

Lesson 4

Math

Unit 2

2nd Grade

Lesson 4 of 21

Objective

Use base ten blocks to represent adding within 100.

Student-Facing

I can use base ten blocks to show my thinking when adding within 100.

Common Core Standards

Core Standards

  • 2.NBT.B.5 — Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Foundational Standards

  • 1.NBT.C.4
  • 1.NBT.C.5
  • 1.NBT.C.6

Criteria for Success

  1. Understand that two-digit numbers are composed of tens and ones.
  2. Compose a given two-digit number using appropriate base ten blocks. 
  3. Combine two sets of built two-digit numbers to find the total. 

Tips for Teachers

  • In this lesson students add 2 two-digit numbers using base ten blocks to support their thinking. Students may choose to count on when adding or they may choose to add ones and then tens. Both are acceptable ways for students to work with adding. If students are counting on, starting with the larger number should be encouraged. 
  • Note: students will need paper base ten blocks and tape to complete the Target Task and #3 on the Problem Set. Students can either cut these out from the template below, or they can be provided with a set. Alternatively, students can use regular base ten blocks and the teacher can walk around to check responses.

Lesson Materials

  • Base ten blocks (7 tens and 9 ones per student or small group)
  • Paper base ten blocks (tens, ones) (5 tens and 7 ones per student)
  • Tape (one roll per small group)
  • Tens place value chart (one per student or small group) — These should be laminated or in page protectors to reuse

Warm Up

5-10 minutes

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Anchor Tasks

15-25 minutes

Problem 1

a.   Use base ten blocks to build the numbers 35 and 14.

b.   Join the numbers by adding. What addition equation does this represent?

Purpose

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Set Up

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Problem 2

a.   Use base ten blocks to model how you would add 44 and 27. 

b.   What equation represents this?

c.   How was finding the total different in this problem than finding the total in Anchor Task 1?

Purpose

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Set Up

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Problem 3

Use base ten blocks to solve the following using your tens place value chart as a work mat.

a.   21 + 19= _____

b.   30 + 26= _____

c.   35 + 27= _____

Purpose

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Set Up

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Problem Set

15-20 minutes

Target Task

5-10 minutes

Problem 1

Based on the images, write the addition equation and solve. 

Student Response

Problem 2

Use the paper base ten blocks to show how you would model and find the solution to the following equation.

34 + 23 =

Student Response

Additional Practice

Daily Word Problems, Warm Ups, and Center Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Next

Use math drawings to represent adding within 100.

Lesson 5
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Adding & Subtracting with Multiples of Ten

Topic B: Strategies for Adding within 100

Topic C: Strategies for Subtracting within 100

Topic D: Working within 100 and Categorical Data

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