As you might recall from math class, pi is the ratio of a circle's circumference to its diameter. This irrational number—approximately 3.14159—shows up quite frequently in many mathematical applications, including geometry and trigonometry.
Try the latest teaching guides from PhET’s Amanda McGarry for #HTML5 Graphing Lines. These activities can be used as part of a three-day sequence or individually. The lessons are aligned with the CCSS in Mathematics and the Standards of Mathematical Practice and include complete outlines as well as annotated activity sheets.
Education researchers are beginning to validate what many teachers have long known: connecting learning to student interests helps the information stick. Here's an example of how one algebra teacher made it work in her class.