Last updated: July 10, 2019
Lesson Plan
Dividing Fractions Using Saguaros
- Grade Level:
- Middle School: Sixth Grade through Eighth Grade
- Subject:
- Math
- Lesson Duration:
- 60 Minutes
Objective
The objective of this lesson is to help students learn how to divide fractions using saguaros.
Background
Tucson, Arizona is home to the nation's largest cacti. The giant saguaro is the universal symbol of the American west. These majestic plants, found only in a small portion of the United States, are protected by Saguaro National Park, to the east and west of the modern city of Tucson. At Saguaro, you have a chance to see these enormous cacti, silhouetted by the beauty of a magnificent desert sunset.
Preparation
Familiarize yourself on saguaros. Be able to talk about its life cycle briefly in class.
Print Saguaro Fraction Worksheet.
Materials
Download Saguaro Fraction Worksheet
Procedure
#1: As a class, watch the video on how saguaros grow in the wild.
#2: Introduce (or re-introduce) fractions to the students. Make sure that they are comfortable with converting a mixed number to improper fraction. Remember that when converting a mixed number, one must multiply the denominator by the whole number and then add the product to the numerator. Write the sum over the same denominator.
#3: Look at the saguaro height table on the Saguaro Fraction worksheet. Notice that the heights are not in whole numbers. This will be a good time to refresh students' memory on converting decimal numbers into fractions.
#4: As a class, convert the first column of Height in Decimals to the Height in Fractions in second column.
#5: Let the students convert the numbers in the third column, Height in Decimals, to Height in Fractions on their own.
#6: The second part introduces students to word problems using division of fractions. Review with students the steps in fraction division. The first step is to convert mixed numbers to improper fractions, or express whole numbers as a fraction (the dividend). The second step is to change the operation from division to multiplication. The third step is to find the reciprocal of the second fraction (the divisor). Finally, the students can perform the operation: multiply the numerator by the numerator and the denominator by the denominator. Express the solution in the simplest form.
#7: Come together as a class and check answers.
Vocabulary
Saguaro- a giant columnar (cylindrical) cacti that is native to the Sonoran Desert
Fraction- not a whole number, has a numerator and a denominator
Rubric/Answer Key
Saguaro Fraction Answer Key