In this lesson, students practice solving for a variable first and obtaining an expression that defines it in terms of the others. They see that doing so allows them to solve problems more efficiently.

Spreadsheets and other computer programs can help illustrate the benefits of isolating a variable. Students see that once a variable of interest is isolated and expressed in terms of all the other variables, a computer program can use that expression to speedily calculate its value when the other variables take on different values. The interactive model is a powerful way to test different assumptions in a situation (MP4).