This resource was reviewed using the Curriki Review rubric and received an overall Curriki Review System rating of 3, as of 2012-02-10.
Technical Completeness: 3
Content Accuracy: 3
Appropriate Pedagogy: 2
This lesson teaches students to factor out a common factor from the sum of two whole numbers, for example, by rewriting 24 + 20 as 4(6 + 5). It creatively uses hands-on scenarios in which students group different kinds of objects into as many identical groups as possible, thus discovering the greatest common factor. This makes the lesson interesting, but some changes are needed for mathematical correctness. Representing “24 girls and 20 boys” as 24g + 20b is misleading, since 24g means “24 times the number of girls”, not “24 girls”. This is an important point, because students must learn to see variables as quantities, not labels. It could be fixed by using variables that represent quantities. For example, if s represents the unknown number of M&M’s in a small bag, and b represents the number in a big bag, then 24s + 20b correctly represents to total number of M&M’s. Adding problems with just numbers, such as 24 + 20, would connect more closely to the stated objective. In addition, students will need more practice with the mistake of finding a common factor that is not the greatest one. Finally, the formatting of the exercises retyped from the publisher could be improved.