Lesson Plan

The Case of the Missing Rectangle Side

Your students will become junior math detectives as they hunt down the missing side of a rectangle by applying the area formula for rectangles. The only clues they have are the rectangle's area and the measure of one side.
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Need extra help for EL students? Try the Area Arrangements pre-lesson.
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Need extra help for EL students? Try the Area Arrangements pre-lesson.

Learning Objectives

Students will be able to find the missing side of a rectangle given the rectangle's area and measure of one side by applying the area formula.

The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.
EL adjustments

Introduction

(10 minutes)
  • Prior to the lesson, draw a large rectangle to display.
  • Tell students that today they will be on the case of the missing rectangle side.
  • Inform them they will need their multiplication, division, and reasoning skills to solve the case.
  • Display the large rectangle. Add to the fun by drawing a magnifying glass and tell students that they are officially on the case of the "missing rectangle side."
  • Tell students that the only clues they have on the case is the area of the rectangle and the measure of one of the rectangle's sides.
  • Write down the label area underneath the rectangle, defining it as the space inside the shape.
  • Next, review the formula for area.
  • Write down the area formula. Demonstrate an example of solving for area.

Beginning

  • Allow students to discuss their ideas in partners in their home language (L1) or their new language (L2).
  • Provide visuals and vocabulary cards in their L1 or L2 for the new terms.
  • Give them sentence frames to help them explain the meaning of the word "area."

Intermediate

  • Have them restate the meaning of the word "area" and its equation for a rectangle in their L1 or L2.
  • Ask them to relay the steps you used to solve the area problem.