How old is the plant? Here is a task that presents the exponential decay function for carbon 14 in a plant. Pupils use the function to estimate the amount of carbon 14 in the plant when it died and analyze the function to find what the half-life of carbon 14 is.

Concepts

exponential decay, exponential equations, exponential models, carbon dating, exponential functions

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Additional Tags

math

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Instructional Ideas

• Lead a discussion on carbon 14 dating and how it is done

Classroom Considerations

• Task can be used as instructional tool or as an assessment
• The class should know how to evaluate an exponential expression

Pros

• The discussion of the solutions reflects upon the idea of half-life and whether the solutions make sense
• Explains the function within the task

Cons

• The first page of the task is a blank page that is unnecessary

Common Core

HSF-IF.C.8.b HSF-LE.B.5