Cost of light bulbs

 

This activity has been updated (2026). See the new activity here:

https://www.yummymath.com/post/light-bulb-cost-comparison/

 

There's a lot of misinformation out there about the cost to consumers of CFL and LED bulbs and the savings in energy and money that could be realized. Let your students "do the math" and realize some of the profit that could be made by changing our ways. This activity makes for a great activity for Earth Day or really any other day of the year.  Lots of math to be explored including work with decimals operations, order of operations, graphing, systems and piecewise functions. The task is accessible for students from 5th grade through high school.

Thanking Jason Kibbe, Chambersburg, PA, middle school gifted support teacher, for his encouragement in updating this activity.