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Can you crack the spy's code?

Algebra 1Functionsabout 3 minCCSS HSF.BF.B.4.aCCSS HSA.REI.B.3

Read a secret note on a train by undoing a code machine.

Lesson Plan

Find the inverse of a linear function by undoing each step in reverse order, and solve linear equations.

  1. Question: Ask what students spot and what they are curious about. Read “Which letter should we send?” aloud. Have each student guess and say why.

  2. Question: Read “How do you get the letters back?” aloud. Have partners explain their guesses to each other.

  3. Big idea: Pause. Ask a student to say the idea in their own words.

  4. Real-world application: Ask: Where else have you seen this?

  5. Your turn: Have students try their own. Ask them to predict before they test.

How to run it

  1. Whole classPut the lesson on the board. At each choice the class votes, then you select the winner.
  2. SoloShare the link, QR code, or post to Google Classroom. Each student gets to take their own path.