Strategies for Subtraction Facts
Est. Class Sessions: 2–3
Students revisit the Subtraction Strategies Menu for the Facts to discuss which strategies seem to be better suited for different subtraction facts. Students then focus on using the Triangle Flash Cards to practice subtraction facts related to the addition facts in Group A.
Content in this Lesson
- Demonstrating fluency with the subtraction facts related to the addition facts in Group A (1 − 0, 1 − 1,
2 − 0, 2 − 1, 2 − 2, 3 − 1, 3 − 2, 4 − 1, 4 − 2, 4 − 3,
5 − 2, 5 − 3, 6 − 2, 6 − 4) [E6]. - Determining the unknown number in an addition or subtraction sentence relating three whole numbers for the facts in Group A [E7].
- Using strategies that apply the properties of addition (e.g., turn-around, compose and decompose numbers) to solve the subtraction facts.
- Using mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten) to solve the subtraction facts.
Daily Practice and Problems A–D
Materials for Students
| Daily Practice and Problems | Lesson | Homework | Assessment | ||
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Student Books |
Student Activity Book |
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Teacher Resources |
Teacher Guide - digital |
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Supplies for Students
scissors
envelope or plastic bag for storing flash cards
Materials for the Teacher
Display of Subtraction Strategies Menu for the Facts (Student Activity Book) ReferenceDisplay of Large Triangle Flash Card Master (Teacher Guide)
Prepared sets of Show Your Strategy Cards Master (Teacher Guide). See Materials Preparation.
Unit 9 Assessment Record
Math Facts Class Record
6 sheets of chart paper
tape
Materials Preparation
Prepare Triangle Flash Cards. Prepare copies of the Triangle Flash Cards: Group A on heavier paper or card stock for each student. Have students cut apart each set and store them in an envelope or plastic bag. Provide each student with two sets, one to use at school and one to take home. Students will need these cards on an ongoing basis.
Prepare Strategy Charts. Display and write one of the following titles on each sheet of chart paper: “Counting Up,” “Counting Back,” “Making 10,” “Using 10,” “Using Doubles,” and “Thinking Addition.” Leave these charts on display throughout the rest of the unit.
Prepare Show Your Strategy Cards. Make 36 copies of the Show Your Strategy Cards Master and cut them apart so you have 72 cards. Select subtraction facts from the table in Figure 1. Record a different fact on each card. See Figure 2. The subtraction facts in each group can be solved using similar strategies. Keep the following cards separate to use for demonstration purposes at the beginning of the lesson: 12 − 10, 10 − 4, 7 − 2, 7 − 5. 14 − 7, and 15 − 7. You will need 4–5 strategy cards from different subtraction groups for each student pair in your class.
Figure 1: Subtraction facts organized by strategy
Figure 2: Prepared Show Your Strategy Card
Assessment in this Lesson
| ASSESSMENT | EXPECTATION ASSESSED |
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| Self-Check with Triangle Flash Cards Teacher Guide - digital |
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Fact Families with Subtraction Triangles with Feedback Box Student Activity Book Pages 439–442 |
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DPP Item C Silblings Teacher Guide - digital |
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