Academic journal article The Science Teacher

To Tan or Not to Tan? Students Learn about Sunscreens through an Inquiry Activity Based on the Learning Cycle

Academic journal article The Science Teacher

To Tan or Not to Tan? Students Learn about Sunscreens through an Inquiry Activity Based on the Learning Cycle

Article excerpt

Science instructors sometimes avoid inquiry-based activities due to limited classroom time. Inquiry takes time, as students choose problems, design experiments, obtain materials, conduct investigations, gather data, communicate results, and discuss their experiments. While there are no quick solutions to time concerns, the 5E learning cycle seeks to minimize time demands (Bybee 1997). I used the phases of the 5E learning cycle--engagement, exploration, explanation, extension, and evaluation--as a guide when creating the following lesson that teaches students about sunscreens and ultraviolet (UV) radiation.


The beginning of the school year is a good time to discuss the importance of sunscreen and ultraviolet radiation because summer is still fresh in the minds of students who are returning from an extended vacation. This lesson would also work well as an end-of-the-year, presummer reminder for students to take care of their skin during the hot summer months. Teachers can also discuss sunscreens and UV radiation at anytime throughout the school year, especially during lessons about the sun and as a reminder for students that sunscreens should be used year-round. This lesson addresses the National Science Education Standards (see "Addressing the Standards").

Content overview

Before beginning the activities outlined in this article, teachers should provide a content overview so that students gain an understanding about UV radiation, skin cancer, and what safety precautions to take. Although the sun is necessary for life, too much sun exposure can lead to adverse health effects, including skin cancer. More than one million people in the United States alone are diagnosed with skin cancer each year (ACS 2005; DFCI 2005; and Naylor 2000).

UV radiation

Because of the dangers of skin cancer, protecting skin from the sun is vital, and sunscreen use is very important. Used properly, certain sunscreens help protect human skin from some of the sun's damaging UV radiation. The wavelengths of light that damage skin are UVA and UVB.

Both UVA and UVB radiation have been linked to skin cancer and a weakening of the immune system (Naylor 2000; Sinha and Hader 2002). The radiation also contributes to premature aging of the skin and can cause cataracts and skin color changes (Kimbrough 1997; Naylor 2000).

UVA rays (320-400 nm), which are not absorbed by the ozone layer, cause tanning in the short-term and aging in the long-term (Alam 2002; Naylor 2000). UVA rays penetrate into the deeper layer of the skin where they break up the elastin and collagen fibers. When this material is damaged, the skin becomes wrinkled. In addition, research shows that UVA rays suppress the immune system of the skin, making it more susceptible to the development of skin cancer (Godar et al. 2003; Sinha and Hader 2002).

UVB rays, which are partially absorbed by the ozone layer, mostly affect the surface of the skin and are the primary cause of sunburn (Alam 2002; Reuther 1998). UVB is a shorter wavelength of light (290-320 nm) than UVA. The shortterm effect of UVB is sunburn and the longterm effect is skin cancer (Naylor 2000; Urbach 2001).

Scientists measure the amount of UV rays that reach Earth's surface to help the public estimate sunlight exposure during outdoor activities and avoid overexposure. The National Weather Service and the U.S. Environmental Protection Agency developed the UV Index to predict the level of radiation exposure (1-11 + scale) expected for each day (EPA 2004). Individuals can use the UV Index as a guide to help protect their bodies from excess exposure to UV rays.

Skin and sunscreen

Everyone, regardless of race or skin color, is subject to the potential unfavorable effects of overexposure to the sun. However, some people might be more vulnerable to certain conditions.

Skin type affects the degree to which some people burn and the time it takes them to burn. …

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