Half-Life

Introduction:

This activity integrates Chemistry and Algebra 2 by using the concepts of half-life and exponential decay. Half-life is a way for students to see a real life use of exponential decay functions.

Learning Outcomes:

• Students will be able to determine the half-life of “Candium”
• Students will be able to determine the equation for half-life.
• Students will be able to set up and solve for the resulting amount and the time for the half-life of “Candium” given a set of conditions whereby they have to use the equation and not just their graph.

Curriculum Alignment:

Chemistry SCOS:

• 1.01 Design, conduct and analyze investigations to answer questions related to chemistry.
• 4.04 Analyze nuclear energy. (Determining the half-life)

Algebra 2 SCOS:

• 2.03 Use exponential functions to model and solve problems.
• 2.04 Create and use best-fit mathematical models of linear, exponential, and quadratic functions to solve problems involving sets of data.

Classroom time required:

• 45-60 minutes

Materials needed:

• 100 pieces of candy with a letter on one side (recommend MMs or Skittles)
• A plastic bag
• Paper towels
• Graphing calculator.

Pre-activities:

• The students need to be able to define half-life.
• The students need to be able to determine the equation of a line using their calculator.
• The students need to be able to solve half-life problems.
• The students need to be able to use logarithms to solve for the exponent in the half-life equation.

Activities:

Students will collect decay data of their candy and write their results on the board and share their trials with the class.

Assessment:

Post Lab Questions

Critical vocabulary:

• Half-life
• Logarithm
• Decay
• Exponential function

Comments:

This activity worked best when the Algebra 2 teacher had students do it after they had learned about half-life in chemistry and exponential functions and logarithms in Algebra 2.