Once students have had a chance to explore functions that grow at linear and quadratic rates, they have all the tools to analyze exponential growth and decay. You can introduce this concept to your students through the Growth of a Smartphone App problem, which offers an easy-to-understand model of how quickly things grow when they grow exponentially. The goal for this unit is for students to understand the difference between linear, quadratic, and exponential growth, and to know when each kind of growth applies to a given situation. At the end of the unit, students should also be able to understand and solve exponential growth problems as they appear on the HSE exam.

SKILLS DEVELOPED

• Using tables, charts, and drawings to model exponential growth.
• Seeing exponential growth models in word problems.
• Distinguishing between situations that can be modeled with linear
  and exponential functions.
• Observing that a quantity increasing exponentially will eventually
  exceed a quantity increasing linearly or as a polynomial function.
• Noticing that in exponential functions, the variable is in the exponent
  position, and interpreting equations accordingly.