Three-Digit Math

Grade Level

Grade 2

Duration

60 minutes

Class Size

25 students

Learning Objectives

By the end of the lesson, students will be able to:

Add and subtract three-digit numbers up to 1000 fluently using place value strategies.
Understand the concept of regrouping (borrowing and carrying) in addition and subtraction.
Solve word problems involving three-digit addition and subtraction within 1000.

Common Core Standards

This lesson addresses the following Common Core State Standards for Mathematics (Grade 2):

CCSS.MATH.CONTENT.2.NBT.B.5
Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
CCSS.MATH.CONTENT.2.NBT.B.7
Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or relationship between addition and subtraction; relate the strategy to a written method; understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds, tens, and ones separately, and sometimes it is necessary to compose or decompose tens or hundreds.

Materials Needed

Base-10 blocks (hundreds, tens, ones)
Whiteboards and markers
Place value charts
Printed problem cards
Manipulatives like linking cubes
Chart paper with problem examples
Differentiated task sheets (above-level, on-level, below-level)

Lesson Outline

1. Opening Activity – (10 minutes)

Objective: Activate prior knowledge of two-digit addition/subtraction and place value.

Begin with a quick review of tens and ones using base-10 blocks.
Show addition and subtraction of two-digit numbers with regrouping.
Display a sample two-digit addition problem on the board, e.g., 47 + 36. Use base-10 blocks to model and solve.
Ask students to share strategies they know.

Tip: Use a think-pair-share format to encourage participation.

2. Explicit Instruction – (15 minutes)

Objective: Introduce three-digit addition and subtraction with regrouping.

Present a three-digit addition problem, such as 234 + 479. Use a place value chart to organize hundreds, tens, and ones.
Model addition step-by-step using base-10 blocks: add ones, then tens, then hundreds, explaining regrouping (carrying).
Emphasize “when ones are more than 9, regroup to tens” and similarly for tens.
Repeat with a subtraction example, e.g., 601 – 284, demonstrating borrowing with base-10 blocks and place value charts.
Write the algorithm alongside the visual model.

Use clear language: “We add the ones place first, then the tens, then the hundreds. When we have more than 9 in one place, we carry over to the next place.”

3. Guided Practice – (10 minutes)

Objective: Practice with teacher support.

Pose 2-3 problems on the board.
Use whiteboards for students to work through problems with real-time feedback.
Call on individual students or pairs to explain their process aloud.
Circulate and assist students who struggle.

4. Differentiated Small Group Activities – (20 minutes)

Objective: Tailor instruction to student readiness levels.

Above-Level Group:
Work on challenging word problems involving three-digit addition and subtraction that require multi-step reasoning. Provide manipulatives and encourage them to create their own problems for peers.
On-Level Group:
Practice solving addition and subtraction problems with regrouping using place value charts and base-10 blocks. Teachers reinforce algorithms and check for conceptual understanding.
Below-Level Group:
Use hands-on materials exclusively (base-10 blocks, linking cubes) for concrete modeling. Focus on simple addition and subtraction within 1000 without regrouping at first, gradually introducing regrouping with physical support. Provide more one-on-one guidance.

Rotate teacher time spent in each group to provide targeted support.

5. Closing & Assessment – (5 minutes)

Objective: Formative check of understanding.

Give a quick exit ticket: one addition and one subtraction problem (e.g., 352 + 147 and 800 – 265).
Collect tickets to evaluate individual fluency and regrouping ability.
Wrap-up with a class discussion on what strategies helped the most.

Assessment & Data Collection

Formative assessment through observation during guided and small group work.
Exit ticket will help assess fluency and accuracy.
Notes on student explanations will inform next steps.

Extension and Home Connections

Encourage students to find and solve real-life problems at home involving adding or subtracting three-digit numbers (e.g., counting toys, money, or steps).
Suggest parents use base-10 blocks or draw place value charts to help.

Reflection for Teachers

Did students grasp regrouping with place value?
Were the manipulative materials effective?
Which group required the most support, and why?
How can follow-up lessons build on this foundation towards mastery?

This lesson plan balances concrete, pictorial, and abstract representations to strengthen understanding according to Common Core progressive standards.

Teaching Instructions