Lesson Plan:

# Fluently Subtracting within 1000

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August 17, 2015
Standards
August 17, 2015

## Learning Objectives

Students will be able to solve subtraction problems within 1,000.

## Lesson

### Introduction (15 minutes)

• Invite students to bring their math journals and a pencil to the class meeting area.
• Tell them to place their supplies on the floor next to them.
• Tell the students that today we're going to learn a strategy for solving subtraction problems within 1,000.
• Let the students know that to solve for these problems they must have a strong grasp of place value, which we will do a review of, before proceeding.
• On the board write “Place Value.” Under this term, write the following:
``````Place: The position of a digit in a number.
10,000s      1,000s      100s      10s      1s
Value: The value of the digit in its place``````
• Ask students what the term place means in regards to a number. As the students share, place the correct definition next to the term.
• Then, ask the students to share what the term value means in regards to a number. As the students share, place the correct definition next to the term.
• Next, come up with a number, for example 14,262, to show the students how to correlate or determine the place and value of specific digits. Make a chart on the board showing these values. For example:
``````               1             4           2          6        2
Place:       10,000s       1,000s       100s       10s       1s
Value:       10,000        4,000        200        60        2
(10,000x1)    (1000x4)     (100x2)    (10x6)    (1x2)``````

### Explicit Instruction/Teacher Modeling (15 minutes)

• Direct the students’ attention to the board.
• Write a few subtraction problems, within 1,000, on the board, such as 887-498 or 978-683.
• Tell the students that the first thing we want to do is rewrite the problem in place value format, as follows: (800 + 80 + 7) - (400 + 90 + 8).
• Next, tell the students that we will add the numbers, on both sides of the equal sign, based on place value, as follows: (800 - 400) + (80-90) + (7-8).
• With student input, continue to solve the above problem until you find the answer of 389.

### Guided Practice/Interactive Modeling (15 minutes)

• Tell the students to pick up their supplies and write down and solve the other problem, 978 - 683, using what’s been termed the "Place Value Method for Subtraction," on the board.
• Ask for volunteers to raise their hands and share with the class the steps involved based on the problem just completed.
• Give the students time to solve the problem.
• As the problem is being solved aloud by the class, write down the steps volunteered by the students on the whiteboard.
• When the problem is done, review it with the class for accuracy. Make sure everyone has the problem written down as a reference for completing their assignment during independent work time.

### Independent Working Time (20 minutes)

• Send the students back to their seats.
• Pass out the Subtraction Math worksheets.
• Walk around and observe the students as they work on completing the assignment.
• Monitor the students as they work, making sure the problems are done correctly, in that they are justifying their answers by showing their work.
• During this time, the teacher will ask questions of the students to make sure they understand the concept of subtracting within 1,000 using place value.
• The teacher will also answer questions by the students, to help them clarify any misconceptions they may have.

## Extend

### Differentiation

• Enrichment: Students can be given an additional worksheet if they finish early, additionally, students may start practicing subtracting four-digit numbers.
• Support: Observe and monitor these students more closely. Get involved in helping the students solve the problems. These students would also benefit from the use of manipulatives.

## Review

### Assessment (10 minutes)

• The students will be assessed based on the comments and feedback from them during the lesson about the assignment and at the conclusion of the lesson.
• They will also be assessed based on the results of the completed problems assigned.

### Review and Closing (15 minutes)

• Bring the students back to the class meeting area.
• Ask for volunteers to share their answers and work for the problems assigned.
• As the problems are reviewed in front of the class, the students will check their answers for accuracy.
• After each problem has been checked for accuracy, ask the class if there are any questions or comments on solving for subtraction problems within 1,000 using place value.