# The Craft of Word Problems

## CONTENTS OF CURRICULUM UNIT 04.05.04

## The Art of Interpreting Percent

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## Lesson 2

Goal: Students will reinforce their understanding of the metric system as it easily relates to percentage. One meter equals 100 centimeters; therefore, one centimeter equals one percent of a meter. Likewise, 50 centimeters equals 50 percent of a meter and 25 centimeters equals 25 percent of a meter. In addition, the students will appreciate that fractions relate to percentage.

Initiation: I will hold up a rope one meter long. I will ask, “I am holding this rope, what percent refers to the entire (whole) rope. I will anticipate answers such as 100% or the whole thing. After a brief discussion about the percentage of the rope I will verify that the entire rope represents 100%, which is the whole rope represented by 1. I will print 100% on the top of an index card and 1 on the bottom of the card then ask for a volunteer to attach it to farthest point on the right of the clothes line at the back of the room. In addition, I will fill out a zero on another card and ask to have that added to the farthest point on the left of the number line.

Secondly, I will fold my rope in half and show the students two equal parts of the rope. The measurement of each half will be 50 centimeters as 50/100 = 1/2. Next, I will dangle one of the pieces such that I am holding only 1/2 of the rope. Then I will ask, “What fraction represents the piece of rope that I am currently holding?” I expect the students will know that 1/2 is the answer that I am looking for. I will then ask, “who can tell me what percentage this rope represents?” I trust some students will know that the rope is now just 50% of its former size. After some discussion, I will label 50% and 1/2 on the index card and ask for a volunteer to attach it to the middle of the clothes line at the back of the room. (At the five meter mark)

Thirdly, I will fold my rope in half again and ask, “What fraction represents the piece of rope I am holding now?” Responses should be 1/4 and 25%. (Attach to clothes line at the 2.3 meter mark) Next I will hold 1/4 of the rope and dangle the balance. I will ask, “Who can tell me what percentage is left over?” I expect answers of 3/4 or 75%. (Attach to clothes line at the 7.5 meter mark)

Finally, I will repeat the process with the students to include the following: 4/4 and 100%, 1/5 and 20%, 2/5 and 40%, 3/5 and 60%, 4/5 and 80%, 5/5 and 100%. The above fractions and corresponding percentages will be added to the class clothes line and the students’ individual number lines. (See Table VIII, IX, X)

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