The lesson helps students explain why addition and subtraction strategies work using place value and the properties of operations. Most students will know basic addition and subtraction facts, but the lesson shows students the “why” behind the operations. The use of pictures and drawings is also encouraged to help students “see” addition and subtraction. The lesson may be used in conjunction with other lessons related to addition and subtraction.
Sample classroom Procedures:
- Ask students: How do you add numbers?
- Allow for responses and discussion. Ask: How do you subtract numbers?
- Allow for responses and discussion. Ask students if there are other methods they can think of to add and subtract numbers.
- Allow for responses and discussion. Introduce Strategies for Addition and Subtraction.
- Distribute Addition and Subtraction Strategies content pages. Read and review the information with the students. Use additional examples as demonstrations for the students. Save the final question for the lesson closing. Use the additional resources to enhance understanding.
- Distribute Activity page. Read and review the instructions. Pair students. Distribute the blocks or other manipulatives. Encourage students to use different strategies to solve the problems. Students may write a rough draft of each explanation and then write a final copy in the spaces provided.
- Once students have completed the work, allow pairs of students to explain how they solved the word problems, reading aloud their explanations. Students responses will vary.
- Distribute Practice page. Check and review the students’ responses. Allow students to share some of the explanations.
- Distribute the Homework page. The next day, check and review the students’ responses.
- In closing, ask students: What is your favorite thing about adding and subtracting numbers? Why?
Common Core State Standards:
None for Grades 1 or 3
Class Sessions (45 minutes): at least 2 class sessions
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