In this lesson, students continue to examine situations characterized by exponential decay. The emphasis here is on analyzing graphs representing such situations. Students work across representations: from graphs to equations and from verbal descriptions to graphs. In addition to interpreting mathematical representations in context (MP2), students also think carefully about how the numbers used in place of \(a\) and \(b\) in an expression of the form \(a \cdot b^x\) influence the graph of the equation \(y = a \cdot b^x\) (MP7).
Lesson overview
 6.1 Warmup: Fractions and Decimals (5 minutes)

6.2 Activity: Falling and Falling (15 minutes)
 Includes "Are you Ready for More?" extension problem
 6.3 Activity: Card Sort: Matching Descriptions to Graphs (15 minutes)
 Lesson Synthesis
 6.4 Cooldown: A Phone, a Company, a Camera (5 minutes)
Learning goals:
 Determine whether situations are characterized by exponential growth or by exponential decay given descriptions and graphs.
 Use graphs to compare and contrast situations that involve exponential decay.
 Use information from a graph to write an equation that represents exponential decay.
Learning goals (student facing):
 Let's compare situations where quantities change exponentially.
Learning targets (student facing):
 I can use graphs to compare and contrast situations that involve exponential decay.
 I can use information from a graph to write an equation that represents exponential decay.
Required materials:
 Preprinted slips, cut from copies of the blackline master
Required preparation:
 Make copies of the blackline master for the Matching Descriptions to Graphs activity, one copy for every 2 students. Cut up the slips and separate into sets ahead of time.
Standards:
 This lesson builds on the standards: CCSS.8.EE.A.1MS.8.EE.1MO.8.EEI.A.1
 This lesson builds towards the standards: CCSS.HSFBF.A.1MS.FBF.1CCSS.HSFIF.B.4MS.FIF.4MO.A1.LQE.A.3MO.A1.IF.B.3
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