**Lesson Plan: Addition and Subtraction (Three-Digit Numbers) for Grade 3**
**Objective:**
Students will be able to add and subtract three-digit numbers with and without regrouping.
**Common Core Standards:**
- CCSS.MATH.CONTENT.3.NBT.A.2: 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.
**Materials:**
- Whiteboard and markers
- Base-ten blocks
- Place value charts
- Worksheets with three-digit addition and subtraction problems
- Math journals
- Pencils and erasers
**Lesson Duration:** 60 minutes
**Lesson Outline:**
1. **Introduction (10 minutes):**
- **Greeting and Objective:** Welcome students and introduce the objective of the lesson: "Today, we will learn how to add and subtract three-digit numbers."
- **Review Previous Concepts:** Briefly review the addition and subtraction of two-digit numbers and the concept of place value (hundreds, tens, units).
2. **Direct Instruction (15 minutes):**
- **Addition with Regrouping:**
- Write an example on the board: 456 + 378.
- Explain each step: Start from the rightmost digit (units), add 6 + 8 = 14, write down 4 in the units column and carry over 1 to the tens column.
- Continue with the tens column: 5 + 7 = 12, plus the carried over 1 = 13. Write down 3 in the tens column and carry over 1 to the hundreds column.
- Proceed with the hundreds column: 4 + 3 = 7, plus the carried over 1 = 8. Write down 8 in the hundreds column.
- **Subtraction with Regrouping:**
- Write an example on the board: 642 - 389.
- Explain each step: Start from the rightmost digit (units), if 2 < 9, borrow 1 from the tens column making it 12 - 9 = 3.
- Proceed to the next column: tens column becomes 3 (original 4 minus 1 borrowed) - 8. Since 3 < 8, borrow from the hundreds making it 13 - 8 = 5.
- Finally, the hundreds column: 5 (original 6 minus 1 borrowed) - 3 = 2.
3. **Guided Practice (15 minutes):**
- Distribute place value charts and base-ten blocks to students.
- Guide students through several examples of three-digit addition and subtraction problems using the place value charts and blocks.
- Allow students to solve problems in pairs and walk around to offer assistance.
4. **Independent Practice (10 minutes):**
- Provide worksheets with three-digit addition and subtraction problems.
- Instruct students to complete the worksheet independently.
- Monitor progress and provide support as needed.
5. **Closure and Review (5 minutes):**
- Review key concepts and steps for addition and subtraction with regrouping.
- Ask students to share any strategies they found helpful.
- Address any remaining questions.
6. **Assessment and Homework (5 minutes):**
- Collect the completed worksheets for assessment.
- Assign a few addition and subtraction problems for homework to reinforce the day's lesson.
**Differentiation:**
- For struggling students: Use more visual aids (like base-ten blocks) and provide one-on-one or small group instruction.
- For advanced students: Challenge them with word problems that require addition and subtraction of three-digit numbers or introduce early concepts of four-digit addition and subtraction.
**Reflection:**
- After the lesson, reflect on what worked well and what could be improved.
- Consider student feedback and performance to plan further lessons on this topic or to identify areas that need additional reinforcement.
**Extension Activities:**
- Introduce simple word problems to apply three-digit addition and subtraction in real-life contexts.
- Use educational math games or digital apps that practice addition and subtraction of three-digit numbers for further engagement.