Guided Lessons

# Modeling Fraction Subtraction

Encourage student explanations and visual representation of fraction subtraction in this interactive lesson. Use this lesson on its own or as support to the lesson Modeling Mixed Number Subtraction.
This lesson can be used as a pre-lesson for theModeling Mixed Number SubtractionLesson plan.

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This lesson can be used as a pre-lesson for theModeling Mixed Number SubtractionLesson plan.

Students will be able to model subtraction with like denominators.

##### Language

Students will be able to describe and ask questions about a visual model for subtraction fractions using colour-coding and peer supports.

(5 minutes)
• Tell students to look at the visual you drew on the board from the example from the Visually Subtracting Fractions worksheet. Ask students to write on their whiteboards what they think about the visual. Encourage them to draw the visual on their whiteboards and label it if they can (e.g., "numerator," "denominator," "subtraction symbol," etc.).
• Ask students to share their boards with their partners and have them talk about what the visual may represent. ("I have ____Because ____. I think ____. The visual shows ____.")
• Conduct a class discussion about the visual and lead them to label the numerator and denominator on the board. Explain the blue coloring is the number they subtract from a fraction problem and the red coloring represents the group of numbers from which it is subtracted.
• Share the meanings of the terms Minuend, Subtrahend, and DifferenceAs you label them with arrows pointed to their represented number in the number sentence 911511.
• Write the student-friendly language objective on the board and have students choral read it with you.
(7 minutes)
• Show students how to represent the subtraction problem with the visual from the top example from the Visually Subtracting Fractions worksheet using one colour to represent the minuend and the other colour to represent the subtrahend. Ask them to copy your teacher markings on their whiteboards as you explain each step using sequencing words and proper vocabulary terms.
• Model checking your answer to the number sentence by recreating the visual without the worksheet Visually Subtracting Fractions displayed. Then, display the worksheet to show you had the correct answer.
• Ask an advanced EL who is confident in the mathematical process to draw a visual model for a new expression, such as 1013513. Encourage them to share why they are completing certain steps and what their final answer is. Listen for the transition phrases and vocabulary words they use in their explanations and write them on the side of the board for students to reference in their future conversations.
• Have the other students copy the presenter's markings on their own whiteboards.
• Model asking the presenter probing questions to help them arrive at the correct answer, or to encourage them to explain their ideas further (e.g., "Why did you add ____Over here? What do you think is missing from the visuals?"). Write some of the questions you use on chart paper labeled "Question Frames" for students to reference in their own peer conversations.
(10 minutes)
• Assign students problem #1 from the Visually Subtracting Fractions worksheet. Allow them to use counters to represent the colors or their colored markers as they complete the first problem.
• Have students turn and talk to their partner to explain their answer for problem #1. If partners do not agree with the answer, have them ask probing questions, such as: "Why did you add ____Over here? What do you think is missing from the visuals?" Continue to add questions you overhear to the Question Frames chart paper.
• Tell students they can use the following sentence frames as support for their conversations:
• "I have ____Dots outside/inside the circle because ____."
• "My answer is ____Because ____."
• Have a pair come up and share their answer using the correct vocabulary and sentence stems from the board.
(10 minutes)
• Instruct students to work in partners to solve the rest of the problems from the Visually Subtracting Fractions worksheet.
• Encourage partners to try the problem on their own and then come together to share their answers and check their answers by trying to recreate the fraction. Ask them to explain their answers to their partner using some of the sentence frames already explored during the lesson.

Beginning

• Allow students to use their home language (L1) or their new language (L2) in all discussions. Provide bilingual reference materials to assist in their vocabulary acquisition.
• Encourage students to use the vocabulary cards and terms in their conversations. Allow them to draw pictures to support their understanding of the terms, especially on the vocabulary cards without images.
• Have students use their counters and do the problem as they explain it to their partner (to act as a visual aid).

• Pair students with mixed ability groups so they can offer explanations and provide feedback to beginning ELs when appropriate.
• Ask them for sentence frames and questions that they think will help partnerships share more details about visuals and answers.
(5 minutes)
• Display the visual representation of 16211021Without the number sentence on the board using proper colour-coding. Ask students to pay attention while you are drawing the visual as it will help them determine the number sentence.
• Tell students to examine the visual and write the number sentence that is shown in the visual on their large index card. Have students check their answer by using their number sentence to recreate the visual without looking at the example on the board.
• Have partners turn and talk to each other, sharing their answer or asking questions about the visual. Encourage them to use the sentence stems listed on Question Frames chart paper.
(3 minutes)
• Ask the following question: How has using colour-coding and the visual subtraction helped you subtract fractions? ("It helps me because ____. I like the strategy because ____.")
• Allow students to turn and talk to each other about their thoughts and write some of the student answers you overhear on the board.
• Share some student answers aloud and tell them they can use this strategy to subtract mixed numbers too.