Stratospheric Ozone Lesson Plans
Summer Scarlatelli
Grade Level
· 8th grade Physical Science, 9th Grade Earth Science or 11th grade Environmental Science
Objectives
· Students will be able to describe where in the atmosphere the ozone layer is located.
· Students will be able to differentiate between O2 oxygen and 03 ozone.
· Students will be able to identify a chlorofluorocarbon and describe how they cause ozone depletion.
· Students will be able to describe how volcanoes affect the ozone layer
· Students will be able to identify how the depletion of the ozone layer is letting in harmful radiation and how this is affecting humans and other organisms.
· Students will be able to use the UV index and describe how to better protect themselves from harmful UV radiation.
· Through research and discussion the students will be able to give an accurate and detailed description of how the lithosphere and the biosphere affect stratospheric ozone and how the depletion of stratospheric ozone layer is affecting the biosphere and hydrosphere.
Key Words
· Ozone or O3, Oxygen or O2, Chlorofluorocarbons, UV-A radiation, UV-B radiation, UV-C radiation, atmosphere, stratosphere, ozone layer, skin cancer, UV Index, catalyst, triatomic molecule, diatomic molecule
Teaching Time
· Five 45-minute class periods (to allow time for research and rehearsals) and one 30 minute class period for class play.
Curriculum and Instructional Strategy
1. Have students take a “Pre-test” survey and grade themselves on how much they think they know about change and the terminology that encompasses it. They will rate themselves 4 – 1, four feeling they know a lot through one meaning they feel that they know very little. The questions will look like the following.
a. How well can you explain ozone depletion?
b. Can you identify what the molecule O2 is?
c. Can you identify what the molecule O3 is?
d. Can you locate the ozone layer in the atmosphere?
e. Can you identify human made products that are harming the ozone layer?
f. Can you identify natural causes that are affecting the ozone layer?
g. Can you describe UV radiation and can you identify the three major types of it?
h. Can identify how UV radiation reaches Earth and can you identify how they affect organisms.
i. Can you describe the UV Index?
j. Can you list five ways to protect yourself from UV radiation?
2. Hook
a. When students come into the class they will be shown the picture below and asked to comment on it. They will also hear the following statistics from www.skincancer.org:
i. “As much as 80 percent of UVR can pass through thin clouds that appear to block the sun, so that you can sunburn even on an apparently cloudy day.”
ii. “Typically, it takes about 15 minutes for a fair-skinned person to develop perceptible sunburn in mid-summer”.
b. Next the students will be split into groups of five and they will write what they know about the ozone layer and what they know about the hole in the ozone layer.
i. As a class the students will combine the information they have compiled and separate them into facts and fiction.
1. This will hopefully dispel any misconceptions.
ii. Next the class will be given the following facts
1. The ozone layer is found in the stratosphere
a. It protects Earth and its inhabitants from harmful UV radiation.
b. It is found most often between six and thirty miles above Earth’s surface.
c. The ozone absorbs UV radiation and helps trap in heat.
i. Without the filtering of the ozone layer, more harmful UV-B radiation would reach Earth’s surface.
ii. In humans overexposure to UV radiation can cause cataracts, skin cancer, premature aging and the weakening of the immune system.
2. The ozone layer is getting thinner primarily because of human made chemicals called CFCs.
a. Winds carry CFCs into the stratosphere where they are broken apart by UV radiation and release chlorine
i. Every atom of chlorine can attack and destroy as many as 100,000 ozone molecules
b. CFC’s can be found in aerosols, Styrofoam products, fire extinguishers, and refrigerants just to name a few.
c. As the ozone layer is depleted more harmful radiation can penetrate through the layer and reach the Earth.
d. In 1985 the Montreal Protocol decided to end all production of halocarbons by 1994 and chlorofluorocarbons in developed countries by 1996. If CFC’s had not been banned, “by 2060, the levels of stratospheric chlorine would have been 16 times above 1980 levels and average global ozone levels would have decreased by two thirds.” (www.skincancer.org)
3. Ozone is made up of three oxygen molecules
4. Even though volcanoes produce small amounts of aerosols, major volcanic eruptions can speed up ozone depletion.
iii. Now the class will split back into groups and create posters on what they were surprised to learn.
3. In class, students will take the Ozone Hole Tour at http://www.atm.ch.cam.ac.uk/tour/index.html in order to better understand the ozone layer and the progression of the hole in the ozone layer.
4. Gumdrop Science
a. The teacher will demonstrate the effects that the depletion of the ozone layer can have on humans.
i. This lab was modified from the Environmental Protection Agency’s Sun Wise Program
ii. Supplies
1. One bag of multicolored gumdrops, toothpicks, flashlight, blue transparency (if you do not have one you can color a blank transparency with a sharpie), purple transparency, clear transparency, white piece of paper.
iii. Procedure
1. Part 1
a. Connect three or four pairs of white gum drops with a tooth pick to simulate a diatomic oxygen molecule, which are present in the air we breathe.
b. Have a student shine the flashlight on one of these molecules while holding the blue colored transparency between the two.
i. The blue transparency is demonstrating how short UV wavelength radiation from the sun can break up diatomic oxygen, leaving the oxygen molecules to form triatomic oxygen or ozone.
c. In the stratosphere ozone meets up with CFCs like CFC 11 so have students make a model of CFC 11 using one black gumdrop for fluorine and thee green gumdrops for chlorine.
d. Stick three toothpicks into the carbon to form a three legged stool. Put a green chlorine atom on each of the free ends of the toothpicks.
e. With the stool standing on the desk, put another toothpick in the carbon and attach the fluorine to it.
f. Lay the CFC molecule and the and the ozone molecule side by side on a white piece of paper
i. The white paper represents the stratosphere
g. Bombard them with simulated UV radiation from your flashlight.
i. The flashlight should be covered with a s purple colored plastic sheet to represent a longer wavelength of UV light
ii. In the end, this lab describe how CFC continue to break apart ozone molecules, leaving the chlorine molecules to attack and break up ozone molecules for many years.
2. Part 2
a. Students will investigate a UV Index
i. The UV index provides a daily forecast of the expected risk of overexposure to the sun. The scale is numbered 1 to 11, 1 meaning the lowest risk of exposure to 11 identifying that there is a high risk of exposure. The UV index takes into account clouds and other local conditions that affect the amount of UV radiation that reaches the Earth all over the country.
ii. Students will go to http://www.epa.gov/sunwise/uvindex.html type in their zipcode and look at the UV index for the present date and time.
iii. Students will then interpret the results
b. The teacher will discuss several ways UV radiation can harm humans
i. Overexposure to UV radiation can increase the likelihood of cataracts forming in the eye of many organisms. Cataracts cause the lens in the eye to look milky and they give the sense of a continuously cloudy vision. If cataracts are not treated they could potentially lead to blindness.
ii. One in every five Americans will develop some type of skin cancer in their life time, and that one American dies every hour. Melanoma is perhaps the scariest form of skin cancer and because it may take ten to twenty years to develop, many doctors feel that it usually occurs from sunburns obtained in the patient’s youth. Two other forms of skin cancer are Basal cell carcinoma and Squamous cell carcinoma. Basal cell carcinomas are slow spreading small and fleshy tumors that grow around the head and neck of an individual. Squamous cell carcinomas are red, patchy and scaly tumors that can grow into large groups and spread to other parts of the body.
iii. Overexposure to UV radiation can also cause our skin to prematurely age, making it look thick, wrinkly and leathery.
iv. Too much UV radiation can also suppress the proper functioning of the body’s immune system.
c. Students will identify ways to protect themselves from harmful UV radiation and make posters to post around school.
i. The list will look like the following:
1. Limit you exposure to the sun, especially between 10am and 3pm where they sun’s rays are at their peak.
2. While out it in the sun you should always wear: polarized sunglasses, hats (wide-brimmed if possible), light weight long-sleeved shirts and plants.
3. Wear sunscreen with an SPF or Sun Protection Factor of 15 or higher. The sunscreen should be applied before exposure to the sun and reapplied continuously throughout the day, especially after swimming or any physical activity.
4. Avoid tanning beds
iv. Assigned Questions
1. Why is ozone good for the atmosphere?
2. How is the breakup of ozone in the stratosphere similar to its formation?
3. How do increases in CFC’s affect the stratosphere and more specifically stratospheric ozone?
4. What is the UV index and why is it important?
5. Student Research and School Play
i. Now that the students have a basic understanding of the ozone layer, the causes of ozone depletion and the effects of ozone depletion has on living organisms the students will compose research papers and then compose scenes for a play to present to the lower school.
ii. The teacher will divide the class into five groups.
1. Each group will represent a different way that either the ozone layer is affected by a sphere or how the depletion of the ozone layer affects a sphere. Each group will be labeled one of the following:
a. Atmosphere and the ozone layer – Students will describe and investigate where the ozone layer is located, what it is composed of and why it is important.
b. The lithosphere and its effect of the ozone layer – Students will investigate how volcanic eruptions affect the ozone layer.
c. The biosphere and its effects on the ozone layer – Students will investigate how human made chlorofluorocarbons are affecting the ozone layer.
d. The depletion of the ozone layer and its affects on the hydrosphere – Students will investigate how the depletion of the ozone layer is affecting the hydrosphere in particularly water circulation and water temperature. Students will also go more in depth and describe how the depletion of the ozone layer is affecting the organisms within the hydrosphere.
e. The depletion of the ozone layer and its affect on the biosphere – Students will investigate how the depletion of the ozone layer is affecting organisms like humans and plants.
2. Students will then split into groups of five, each having an expert in one of the five fields.
a. They will then create a five to ten minute skit based on their cumulative knowledge on the importance of the ozone layer and how it affects and how it affected by other spheres.
b. Before preparing the skits they will be told by the teacher which grade level their skit needs to be modified for (PreK/K, 1st/2nd, 3rd/4th or 5th/6th)
c. Students must emphasize sun safety in their skits.
d. Students must make their skits appropriate for the age level they are presenting their skits to
e. After the play, students will then ask the class if they have any questions.
6. Extra Credit
a. For extra credit students can create a school policy or a “Sunwise Policy” to protect themselves and their fellow students at school. The policy should include how to make students more aware of sun safety and how the students can ensure that there is enough shade around school to protect faculty and students from the sun.
7. Have each student retake “Pre-Test” survey and compare their results.
a. Include the following questions
i. Can you identify five ways to protect yourself from harmful UV radiation?
ii. Can you name two things you can do on your own to help stop ozone depletion?
iii. Can you define a catalyst and can you identify one that aids in ozone depletion?
iv. Can you define and differentiate between a triatomic molecule and a diatomic molecule?
v. Can you describe how describe how photochermical reactions are involved in the creation and destruction of stratospheric ozone?
Teacher Rubric
1. The teacher will evaluate the student’s depth of understanding of global climate and class participation through the following rubric. Each category will be graded on a four to one scale, four meaning the student became an expert in the area while a one means that student did not actively participate in the activities or did not pay attention.
a. Knowledge of Stratospheric ozone and in-class participation
i. Students will be able to differentiate between O2 oxygen and O3 ozone.
ii. The student can explain the layers of the atmosphere and identify where the ozone layer is located.