Lesson 1

Lots of Flags

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Lesson Narrative

In this unit students will be applying proportional relationships to solve problems with fractional ratios, rates, percents, and constants of proportionality. The purpose of this lesson is to start the unit with an engaging activity where these arise naturally, in the scaling of flags and in questions about what percentage of the flag is taken up by a particular part of the design. 


Learning Goals

Teacher Facing

  • Compare (orally and in writing) the dimensions and scale factors of multiple scaled copies of the same figure.
  • Explain (orally) how to estimate or calculate the percentage of a rectangular area that is covered by another region.
  • Generate the dimensions for a scaled copy of an original figure that has fractional side lengths.

Student Facing

Let’s explore the U.S. flag.

Learning Targets

Student Facing

  • I can find dimensions on scaled copies of a rectangle.
  • I remember how to compute percentages.

CCSS Standards

Building On

Building Towards

Glossary Entries

  • percentage

    A percentage is a rate per 100.

    For example, a fish tank can hold 36 liters. Right now there is 27 liters of water in the tank. The percentage of the tank that is full is 75%.

    a double number line

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