Carbon 14 Dating Lesson Plan for 10th Grade Example Students

Topic: Carbon 14 dating: How equations of exponential decay can be used to determine the dates of organic material

Objectives & Outcomes

• Understand how carbon-14 dating is used to determine the age of organic materials
• Be able to apply the principles of carbon-14 dating to real-world situations

materials

• Organic material (e.g. bone, wood, plant tissue) that is suspected of being old
• Radiocarbon dating kit (available from any chemistry lab)
• Calculator
• Graph paper or computer software for plotting graphs

Warm-up

• Show students a picture of an organic material (e.g. bone, wood, plant tissue) that is suspected of being old.Ask them to consider what factors might make it difficult to determine the age of the material just by looking at it.

Duration: 5 minutes

Direct Instruction

• Introduce the concept of exponential decay and explain that it is a phenomenon in which a quantity decreases at a rate that is proportional to its current value.
• Using the equation for exponential decay, show how the rate of decay can be calculated based on the starting quantity and the half-life of the material being dated.
• Explain that the half-life of a material is the time it takes for half of the original quantity to decay.Show how the half-life of a material can be used to determine the age of the material based on the calculated rate of decay.
• Use the example of Carbon-14 dating to demonstrate the use of exponential decay equations in dating materials.
• Discuss the limitations of exponential decay and other dating methods, such as radioactive dating.

Guided Practice

• Have students work in small groups to apply the concept of exponential decay to a hypothetical situation in which a quantity is decreasing at a rate that is proportional to its current value.
• Have each group present their scenario and explain how they calculated the rate of decay and the age of the hypothetical quantity using the half-life of the material.

Independent Practice

• Have students choose a real-world example of a radioactive material and use the concept of exponential decay to calculate the age of the material using its half-life.
• Encourage students to create a presentation or report to communicate their findings to the class.

Closure

• Review the key concepts of exponential decay and how it can be used to calculate the age of organic material based on its half-life.
• Ask students to share what they found most interesting or compelling about the topic.

Assessment

• Have students complete a quiz or test that includes questions about exponential decay, half-lives, and the dating of organic material.
• Evaluate their reports on the organic material they dated as a formative assessment of their understanding of the material.