Investigating Addition and Subtraction

50 min.

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Wonder of the Day #158

How Is a $1 Bill Made?

Objective

Students will investigate the inverse relationship between addition and subtraction facts to help solve problems independently and quickly.

Big Idea

If you know the answer to an addition fact, you know the answer to a subtraction fact with the same numbers. They are related.

Put up the question, "How is addition like subtraction?" Students write/draw or use both to explain their thinking on one side of an index card. They share their thinking with a math partner.

Pull up wonder #1470 How is addition like subtraction? and watch the video. Then read through the answer to the question paragraph by paragraph having student volunteers explain what is being taught at the end of each paragraph. Students should ask questions as the answer is being read and explored. Then do the "Test Your Knowledge" quiz as a whole group. Students will write their answer on individual whiteboards and show the answer to each question as they are read. Teacher can use as formative assessment to gauge concept understanding and can either move on or reteach based on answers given. Then student use their whiteboards to teach what they learned about addition and subtraction to a partner. Teacher listens in as another way to assess and reteach if necessary.

Students go back to seats and turn over the index card. Students will once again answer the question, "How is addition like subtraction?" Teacher collects to use as a check for understanding.