SISL > 2012 Sustainability in Math Workshop > Activities > Should I Unplug?

Should I Unplug?

This page is authored by Lori Carmack of Salisbury University, inspired by a presentation by Victor Donnay, Bryn Mawr College, at the 2013 MAA PREP Workshop: USE Math on Your Campus at Shippensburg University. Workshop organizers: Corrine Taylor (Wellesley College), Ben Galluzzo (Shippensburg University), James Hamblin (Shippensburg University).
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see

This page first made public: Sep 17, 2013


A wide variety of electronic devices and small appliances are a regular part of students' lives: cell phones, laptops, iPods/MP3 players, hairdryers, irons, coffeemakers, printers, mini-refrigerators, microwaves, televisions, etc. Many of these products remain plugged in while not in use in students' dorms or apartments. In this project, students investigate the question "Should I unplug?" In particular, students measure plug loads of several products using a wattage meter, then compute the monetary costs associated with various unnecessary plug loads.

Learning Goals

In this activity, students learn about plug loads, measure plug loads of various electronic devices and small appliances using a wattage meter, better understand conversion factors, and learn to translate standard AC electrical usage into an equivalent dollar value. In addition, they think about the broader implications of unnecessary energy consumption, and prepare and present the results of their computations.

Context for Use

This activity requires only basic computational skills and is intended for small groups. It is based on a National Energy Education Development (NEED) Project ( The NEED Project is designed for the intermediate and secondary level; this activity is appropriate for a math for liberal arts or quantitative reasoning course at the collegiate level. The project should take approximately one week and consists of three parts: a) an in-class activity and preliminary example calculation, b) independent student calculations, and c) a summary presentation. Necessary equipment for the in-class portion includes a wattage meter, students' cell phones with chargers, and various other small appliances and electronic devices. Plug loads for many products can be found online.

Description and Teaching Materials

Plug Load In-Class Activity (Microsoft Word 2007 (.docx) 18kB Sep16 13)

Teaching Notes and Tips

A crucial component of the project is to carefully walk students through a sample calculation converting wattage usage into an equivalent dollar value.


Students will be assessed based upon a final presentation of their computations.

References and Resources