Mathigon
Mathigon: Math Foundations: Divisibility and Prime: Greatest Common Factors
This lesson focuses on the greatest common factors it poses real situations and asks students answer them and then it provides more information and more exercises.
Calculator Soup
Calculator Soup: Greatest Common Factor Gcf Calculator
Calculate GCF, GCD, and HCF of a set of two or more numbers and see the work using factorization. An interactive calculator, explanations, and examples are included.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Greatest Common Factors, Least Common Multiples
Math Forum response to request for info on how to find greatest common factors, and how this compares to least common multiples. Explanation includes examples of each.
Khan Academy
Khan Academy: Gcf & Lcm Word Problems
Solve word problems where you either need to find the GCF or LCM. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
PBS
Pbs: Greatest Common Factor
In this video, learn how to find the greatest common factor of two numbers. Then, see how this can be used to solve problems with large numbers. In the accompanying classroom activity, students learn to find prime factors using factor...
Better Lesson
Better Lesson: Greatest Common Factor
Sixth graders will learn how to find the Greatest Common Factor of two or more numbers by using math manipulatives.
Wolfram Research
Wolfram Math World: Greatest Common Divisors
An advanced investigation of Greatest Common Factors (Divisors) and a look at related algorithms and properties) comutative, associative, and more). Contains links to relevant topics.
University of Vienna (Austria)
University of Vienna: Pulling Common Factors Out
Multiple choice assessment which tests knowledge of "simple" factoring (greatest common factor only), given varying degrees of polynomials.
Khan Academy
Khan Academy: Greatest Common Factor
Find the greatest common factor of 2 or 3 integers. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Wyzant
Wyzant: Factoring a Gcf From an Expression
The tutorial explains how to factor a greatest common factor from an expression. The resource includes a lesson with examples, practice problems, and an expression-factoring calculator.
Wyzant
Wyzant: Finding a Gcf
In this lesson from WyzAnt, students learn how to find the greatest common factor (GCF) for numbers and expressions. There are practice problems and a GCF calculator for assistance.
Wyzant
Wyzant: Factoring a Gcf From an Expression
This tutorial demonstrates how to factor the GCF out of a polynomial expression. An online worksheet is provided for extra practice.
Quia
Ixl Learning: Greatest Common Factor
Brush up on your math skills relating to the greatest common factor then try some practice problems to test your understanding.
Shmoop University
Shmoop: Basic Operations: Lcm & Gcf
Students learn about the least common multiple and the greatest common factor. The resource consists of notes, step-by-step examples, and practice problems with solutions.
Free Math Help
Free Math Help: Greatest Common Factor
The lesson investigates the greatest common factor. Explanations and sample exercises are provided.
Wyzant
Wyzant: Factoring a Gcf From an Expression
Students review factoring a greatest common factor from an expression. The handout consists of an example and answer sheet.
Other
Greatest Common Factor/definition and Example
A walkthrough example of the discovery of the GCF of three numbers. Contains a definition as well.
University of Waterloo (Canada)
University of Waterloo: Cemc: Math Circles: Number Theory Ii [Pdf]
This worksheet provides a series of problem-solving questions that require higher order thinking skills. Questions will include finding the greatest common divisor, and least common multiple.
McGraw Hill
Glencoe: Self Check Chapter Test Fractions and Decimals
Students are assessed on fractions and decimals. Topics include greatest common factor, improper fractions, and fractions as decimals. The self-checking test includes hints and solutions.
AAA Math
Aaa Math: Practice Finding Greatest Common Factor
This lesson contains a learning exercise in which the user has to find the greatest common factor and type it in. The exercise keeps track of how many right and wrong answers given and gives you a grade.
National Council of Teachers of Mathematics
The Math Forum: Finding the Greatest Common Factor of Two Numbers
Math Forum response to question about finding the greatest common factor by using the factoring tree method.
Amby Duncan-Carr
Amby Duncan Carr: Amby's Math Resources
Amby's Math Resources site is a tutorial that explains finding the greatest common factor. It also has examples that are done for you step by step, as well as examples for you to try (and check) on your own.
Cool Math
Coolmath: Gcf's and Lcm's Common Factors
These prealgebra-arithmetic lesson explains greatest common factors (GCF's)and shows how to find them.
Math Slice
Math Slice: Greatest Common Divisor (Factor): Math Worksheets
This tool allows you to create worksheets where students must find the greatest common factor in a set of two to four whole numbers.