📊Lesson 2.5 Outline- Subtracting Zeros in Standard Algorithm (For Teacher-Do Not Publish)

For full lesson outline, see Advantage Math.

Standards: 

4.NBT.4: Fluently add and subtract multi-digit whole numbers using the standard algorithm. 

 

Objectives: 

Math Objective: I can subtract multi-digit whole numbers with zeros in the minuend.

Language Objective: I can discuss how to subtract across zeros using the standard algorithm with students.

 

Vertical Alignment:

3.NBT.2: Fluently add and subtract within 1,000 using strategies and algorithms vbased on place value, properties of operations, and/or the relaitionship between addtion and subtraction.

4.NBT.4: Fluently add and subtract multi-digit whole numbers using the standard algorithm. 

5.NBT.7: Add,subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. 

Common Misconceptions: 

  • When subtracting across zeros, students may “take” from one place and “give” to a place not directly to the right.
  • There are three strategies for subtracting with zeros in the minuend: standard algorithm, counting up, and constant difference. Counting up is used for smaller numbers, typically within 1,000. The standard algorithm is used for larger numbers when one or two digits are zeros or the zeros occur in the middle of a number. Constant difference is used as a standard algorithm in the next lesson and takes the place of the traditional method of regrouping multiple times across zeros.

Lesson Outline: 

🚀Launch:

Students will record or type their response to the subtraction question. 

  • It is helpful to use manipulatives like base ten blocks. 
  • Point out how to identify when regrouping needs to happen and how.
  • Teacher should either walk the class through the problem or make a video for remote learning. (See Advantage Math for specific steps.)

🤔Explore:

  • Students have two questions to answer. The recording charts with the first steps are included to help them. 
  • Teachers should be present and observing as students work through these problems. 
  • Students might still benefit from a think a loud as the teacher walks through the problems. 

💬Discussion:

Students explain how to make more ones when needed. 

  • This could be a good resource for struggling students. Select good responses and share with the class. 

✅Exit Ticket:

Students will solve a subtraction problem with zeros in the minuend then reflect on how they are feeling about the lesson. 

Additional Resources: 

Differentiation: 

    • Challenge: For students who need a challenge, present the fish problem again and ask them how they might solve this type of problem using mental math (counting-up strategy).

Struggling: For students who are struggling with the standard algorithm, use a large place value board with base-ten blocks or place value disks. Start with problems such as 500 − 237 or 505 − 237 and work up to the larger problems.