In case you are trying the MARS MAP Classroom Challenges for the first time, it is recommended that you read the Brief Guide for teachers and administrators before you get started.
The lesson begins with a whole-class introduction, in which students review their understanding of the meanings of GCF and LCM. They then examine some sample student work and evaluate the different approaches taken.
Students then take part in a collaborative task, in pairs or groups of three, in which they complete a grid, finding numbers to satisfy different constraints of greatest common factor and least common multiple. As they do this, they learn more about how these quantities are related to each other and to the numbers.
In a whole-class discussion, students then consider their approaches to the task and share their conclusions.
To help you to assess how well students are able to understand the meanings of the terms 'Greatest Common Factor' (GCF) and 'Least Common Multiple' (LCM).
To identify and help students who confuse GCFs and LCMs.
To identify and help students who lack a sense of what values of GCF or LCM might be reasonable for a given pair of numbers.