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Time is a ruler

7th GradeProportional relationshipsabout 2 minCCSS 6.RP.A.3.bCCSS 7.RP.A.2.b

Count the seconds after a flash. Then map the sea floor with echoes.

Lesson Plan

Use distance = speed × time to find distances from timed signals, from sound to light.

  1. Question: Ask what students spot and what they are curious about. Read “How far was that lightning?” aloud. Have each student guess and say why.

  2. Question: Read “How long, there and 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. 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.