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Comparing Sunscreens

This activity is taken from Earth Science With Computers by Robyn Johnson, Gretchen Stahmer DeMoss, and Richard Sorensen, Published by Vernier Software (more info) . This Starting Point page was created by Robert MacKay, of Clark College .
This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


Students use a microcomputer connected to an ultra-violet sensor to compare the relative blocking power of different SPF sunscreens for the UVB region of the solar spectrum.

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Learning Goals

  • Use a microcomputer and UVB sensor to measure UVB radiation (320 nm to 290 nm)
  • Determine the amount of UVB light allowed through different SPF sunscreens.
  • Analyze the trend in UVB intensity vs. SPF values.
  • Learn what SPF means.

Context for Use

This activity can be used as a lab activity in an introductory geoscience course that contains a discussion of UV radiation, environmental health, solar energy, or stratospheric ozone depletion.

Instructors could also use aspects of this activity in an interactive lecture.

Teaching Materials

This activity requires a microcomputer, multi-sensor interface, and UVB sensor. The specific activity is included in Earth Science With Computers by Robyn Johnson, Gretchen Stahmer DeMoss, and Richard Sorensen published by Vernier Software (more info) , with a site license for $45.00. The complete activity in pdf format can be viewed at Comparing Sunscreens The cost of the interface and UVB sensor are $220and $99 respectively. An UVA sensor is also available for $99 and can be used for an extension to this lab.

Students can also use a graphing calculator with the interface and sensor.

Teaching Notes and Tips

This activity will take approximately 2 hours to complete in a lab setting with some extra time possibly needed for students to answer questions and summarize their results. The activity description at Comparing Sunscreens comes complete with two pages of Teacher Information.

Doing parts or all of this activity as an interactive lecture is also an option.


The activity comes with very specific instructions and related questions. The Teacher Information section contains answers to most questions for easy assessment of student understanding. "Extension" ideas are also provided. Having students design their own experiment for an "Extension" investigation can also help you better assess their ability to synthesize what they have learned and to apply this knowledge to a slightly different situation.

In addition to the extension activities suggested by the authors, students could also be asked to research the relationship between UV exposure and skin cancer and to summarize their findings in a short report.

References and Resources

Vernier Software (more info) has several other sample geoscience labs from "Earth Science With Computers" available in pdf format as examples at http://www.vernier.com/products/books/esv/. These include "Where is North", "Reflection and Absorption of Light", and "Water Quality-TDS (Total Dissolved Solids)".

Pasco Scientific has about 13 online lab activities available for free. These are mostly geared towards high school students but can easily be modified for an introductory college level course as either a laboratory activity, a special project, or an interactive lecture example.