Lesson - Tracking UV

GOALS
To use research to gather information about the UV index; to understand scientific inquiry through careful observation and simple experiments

BACKGROUND
The UV index helps forecast the amount of UV radiation reaching the earths surface at solar noon. This system of measurement ranges from 0 (low level) to 15 (dangerous level). The index depends on factors that include latitude, elevation, ozone, and local air pollution. To block both UVA and UVB rays, its best to use broad spectrum protection sunscreens that contain Avobenzone (Parsol 1789), zinc oxide, or titanium dioxide.

A sunscreens Sun Protection Factor (SPF) number indicates how powerful the sunscreen is in preventing sunburns. It can be used to estimate how many times longer a person can stay in the sun before burning than without sun protection. Adults should always use sunscreen with SPF 15 or higher, and children benefit from SPF 30 or higher. Remember, sunscreen works differently for everyonefair-, red- and blond-haired people with freckles will burn much faster than people with dark hair, skin, and eyes.

PREP
Photocopy several weather forecasts from a newspaper or Internet sources to review with students. Explain a forecast and what the UV index measures. Then create a classroom weather board (based on the chart below) where you post daily high and low temperatures, weather conditions, and the UV index. Finally, distribute copies of the Tracking UV*student reproducible (p. 9) to your students.

CITY NAME	M	T	W	T	F
high temperature (F)
weather (sun, rain, clouds, snow, etc.)
UV index

ACTIVITY

1. Explain the UV Index Chart on the Tracking UV Student Reproducible. Ask: What numbers show a high UV index? (79) What should you do when there is a UV index of 2? (Wear sunglasses, hat, and sunscreen.) What UV index numbers indicate you could burn in 30 minutes? (56)
   
   
2. 2. Visit www.coppertone.com and click on the UV Index tab to search for any citys UV index. As a class, study a city for two weeks. Create a weather board based on the chart above to track the weather in your selected city.
   
   
3. 3. Designate a daily time for students to gather data for the weather board using the Internet, newspapers, and/or television.
   
   
4. 4. Assist students in noticing patterns and drawing conclusions from their data.
   
   

WRAP-UP
Discuss these answers to the Tracking UV Student Reproducible:

Question 5. Temperature should have little or no effect on UV rating as indicated by their data.

Question 6. Clouds or rain should have some effect on the UV index as indicated by their data. (Although clouds or rain can lower the UV index slightly, you still need to wear a hat, SPF 15 or higher sunscreen, and sunglasses to protect yourself—even when the UV index is low.)

Question 7. UV index should increase with elevation.