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Two teams, one mountain

GeometrySimilarityabout 2 minCCSS HSG.SRT.B.5CCSS HSG.SRT.C.6CCSS HSG.MG.A.3

Dig a tunnel from both ends and meet in the middle.

Lesson Plan

Use similar triangles to find directions and distances that cannot be measured directly.

  1. Question: Ask what students spot and what they are curious about. Read “How far apart were their floors?” aloud. Have each student guess and say why.

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

  3. Question: Read “One degree off. How far by the middle?” aloud. Have partners explain their guesses to each other.

  4. Big idea: Pause. Have partners explain the idea to each other.

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

  6. 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.