# Fluently Subtracting within 1000

Start your students on subtracting three-digit numbers with this lesson that breaks the problems down by place values!
Need extra help for EL students? Try theSharing the Subtraction ProcessPre-lesson.
Need extra help for EL students? Try theSharing the Subtraction ProcessPre-lesson.

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

The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.
(15 minutes)
• Invite students to bring their maths 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.
• Write “Place Value” on the board. 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 PlaceMeans in regards to a number. As the students share, place the correct definition next to the term.
• Ask the students to share what the term ValueMeans in regards to a number. As the students share, place the correct definition next to the term.
• 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)``````
(15 minutes)
• Direct the students’ attention to the board.
• Write a few subtraction problems, within 1,000, on the board, such as 887 – 498Or 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, based on place value, as follows: (800 – 400) + (80 – 90) + (7 – 8).
• Model how to regroup when you cannot solve the subtraction within one place value.
• Continue to solve the above problem, with student input, until you find the answer of 389.
(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.
(20 minutes)
• Send the students back to their seats.
• Pass out the Subtraction maths 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.

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.

Enrichment:

• Students can be given an additional worksheet if they finish early. Additionally, students may start practising subtracting four-digit numbers.
(10 minutes)
• Distribute scratch paper to students and have them solve this problem: 764 - 389.
• Remind them to solve it using the place value strategy.
• Have students submit their solution as an exit ticket.
(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.