# 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.

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.