Lesson Plan Title: Adding and Subtracting Fractions ... - GeoGebra

Title: Adding and Subtracting Fractions
Author: Megan Yanes (m_yanes@yahoo.com)
Grade Level: 6 th , 7 th
Time Frame: 20 minutes
Lesson Plan
Learning Outcomes
Students will visualize solutions to addition and subtraction problems with fractions. Students will also
be able to use this dynamic worksheet as a check when doing addition and subtraction problems on
pencil and paper.
Prerequisite Knowledge
Students should have already been introduced to addition and subtraction of fractions, but mastery is not
necessary.
Student Materials
Add_Sub_Fractions.html
Colored pencils (red, blue, and purple only)
Rulers
Teacher Materials
Add_Sub_Fractions.html
ASFrac_Lesson_Plan

Technology
Latest version of Java
GeoGebra
Procedure
Teacher should investigate the answers to the questions on the dynamic worksheet with the students
and guide them in discovering the rules for addition and subtraction. Here are the rules:
Addition:
numerator = (red + purple) + (blue + purple)
Subtraction (assuming you are subtracting blue from red):
numerator = (red – blue)
For both operations, the denominator is the same:
total number of small congruent rectangles
Checking for Understanding / Assessment
Students should be given problems to practice with and should do these problems on pencil and paper
and with the tool. Also give students several problems and ask them to draw what the solution would
look like (this is where you will need the colored pencils and rulers). Students should turn this
assignment in, along with the rules that they developed in groups, at the end of class. The following
day, there should be a class discussion about this investigation.