Teaching
Guide
The Dual Nature of Ozone:
TROPOSPHERIC OZONE
Adapted by Remelia Arpino from the Rice Air Curriculum
by Daniel Cohan and Kavita Venkateswar
OBJECTIVE
In the previous lesson, students were made aware of the dual nature of ozone, that there is
stratospheric ozone and tropospheric ozone. Stratospheric ozone is important to humans and other life
forms on Earth because it shields organisms from the harmful ultraviolet radiation of the sun. However,
tropospheric ozone or ground level ozone is considered an air pollutant that can harm humans, plants
and other life forms on the Earth’s surface.
In this lesson, the tropospheric ozone will be covered in detail. Students will understand the
chemistry of how tropospheric ozone is formed and its effects on human health and other organisms.
They will also be involved in an inquiry lab where students will correlate meteorological factors with
tropospheric ozone levels. As an evaluation, they are going to write an essay as a form of individual
reflection on how they can help in reducing the intensity of this air pollutant.
Figure 1. Tropospheric ozone is a major component of smog. Credit: U.S. Environmental Protection Agency
TEXAS STANDARDS
TEXAS ESSENTIAL KNOWLEDGE AND SKILLS (TEKS)
Environmental Systems TEKS 9: The student knows the impact of human activities on the environment.
The student is expected to:
A. Identify causes of air, soil, and water pollution, including point and nonpoint sources;
B. Investigate the types of air, soil, and water pollution such as chlorofluorocarbons, carbon
dioxide, pH, pesticide runoff, thermal variations, metallic ions, heavy metals, and nuclear
waste;
C. Examine the concentrations of air, soil, and water pollutants using appropriate units;
D. Describe the effect of pollution on global warming, glacial and ice cap melting, greenhouse
effect, ozone layer, and aquatic viability;
E. Analyze past and present international treaties and protocols such as the environmental
Antarctic Treaty System, Montreal Protocol, and Kyoto Protocol.
TEXAS COLLEGE AND CAREER READINESS PROGRAM (CCRS)
SCIENCE STANDARDS WITH PERFORMANCE INDICATORS
I.
Nature of Science
A.
Cognitive skills in science
1. Use creativity and insight to recognize and describe patterns in natural phenomena.
2. Rely on reproducible observations of empirical evidence when constructing,
analyzing, and evaluating explanations of natural events and processes.
B.
Scientific Inquiry
1. Design and Conduct scientific investigations in which hypotheses are formulated
and tested.
C.
Collaborative and Safe working practices
1. Collaborate on joint projects.
2. Demonstrate skill in the safe use of a wide variety of apparatuses, equipment,
techniques, and procedures.
D.
Current scientific technology
1. Use computer models, applications, and simulations
E.
Effective communication of scientific information
1. Use several modes of expression to describe or characterize natural patterns and
phenomena. These modes of expression include narrative, numerical, graphical,
pictorial, symbolic and kinesthetic.
II.
Foundation Skills: Scientific Applications of Mathematics
A.
Understand the real number system and its properties
1. Calculate the sums, differences, products and quotients of real numbers.
III.
Foundation Skills: Scientific Applications of Communication
A.
Scientific Reading
1. Set up apparatuses, carry out procedures, and collect specified data from a given set
of appropriate instructions.
B.
Presentation of scientific /technical information in appropriate formats for various
audiences
1. Prepare and present scientific/technical information in appropriate formats for
various audiences.
C.
Research skills/information literacy
1. Use search engines, databases, and other digital electronic tools effectively to locate
information
IV.
Cross-Disciplinary Themes
A.
Change over time/equilibrium
1. Recognize patterns of change
V.
Environmental Science
A.
Earth systems
1. Know the major features of the atmosphere
B.
Human practices and their impacts
1. Understand how human practices affect air, water and soil quality.
ENGAGE
Teacher Notes: In this game, students will recognize good and bad ozone. They are going to tap
the good ozone (stratospheric ozone) because it is important and zap the bad ozone (tropospheric ozone)
because it is harmful.
Teacher Preparation: The Engage and Explore activities require the use of computers. If your
access to computers is through your school’s computer lab, be sure to schedule your classes in advance
for this lesson.
Material:
 Computer (preferably one student per computer if possible)
Procedure:
1.
2.
3.
3.
Have your students type: http://spaceplace.nasa.gov/ozone/ to their internet browser.
Ask them to read the information first on the page before clicking the ‘play game.’
Let them play the game for five (5) to ten (10) minutes.
After the game, ask the following question;
a. Why did you tap some ozone molecules and zap the other ozone molecules?
b. Where can you find these ‘good ozone’ and ‘bad ozone’ in the atmosphere?
EXPLORE
Teacher Notes: The ‘ Save Smog City 2 from Ozone’ activity is an interactive simulator that
introduces students to weather and emission factors that have some effect in the concentration of
tropospheric or ground level ozone in the atmosphere. In this simulation, they are going to manipulate
these factors and observe the rise and fall of ground level ozone and how it affects the human health.
This activity will open some ideas necessary for their inquiry lab in the latter part of the lesson.
Materials:
 Smog City 2 Worksheet (SM-1)
 Computers
 Pens/pencils
Procedure:
1. Ask students to type: http://www.smogcity2.org/smogcity.cfm?preset=ozone to their
internet browser.
2. Distribute SM-1 (Smog City 2 Worksheet) to individual students.
3. Before they start , have them locate and read the following;
a. Weather and emission controls on the left side of the page
b. The current temperature reading of 110F in the middle of the page.
c. Information box at the bottom of the page
d. Ground level AQI (Air Quality Index) box at the lower right corner of the page.
Teacher Notes: It might be helpful to go over the AQI for ozone (Table1) first before students
start the simulation so they will get familiar with the different colors and their corresponding
descriptions and cautionary statements.
Table 1. Air Quality Index for Ozone. Credit: airquality.weather.gov
4. Once students are ready, ask them to start the simulation by following the instructions in
the ‘Save Smog City 2 Worksheet. ‘
5. Remind them to answer the corresponding questions for each scenario in their worksheet.
EXPLAIN
Teacher Notes: The procedure below utilizes the ‘Jigsaw Grouping Strategy.’ It is not mandatory
for you to use the same cooperative learning strategy. You can use any other strategies deemed to fit
your classes.
Teacher Preparation: Make copies of the Expert Group Cards. If you have 30 students in the
class, you will have five (5) groups with 6 students per group. Each group will have a representative to
go to each Expert Group. Student assigned as #1 will go to expert group 1, student assigned as #2 will go
to expert group 2, etc. With a group of 5, you need 5 copies for each expert group card.
Vocabulary
 Tropospheric ozone
 NOx
 VOCs
 Meteorological factors
 Humidity
 Chlorosis
 Allergens
 Asthma
Materials:
 Expert Group Card (SM-2) for each group
 Pens/pencils
Procedure:
1. Group students into five (5) with six (6) students for each group. This will be their jigsaw or
home group.
2. Discuss the explore activity briefly by asking the concluding questions in the ‘Save Smog City
2 Worksheet’.
3. Collect the completed worksheet.
4. While they are in their jigsaw or home group, assign each student in the group a particular
number (Student 1, 2, 3, 4, 5, and 6).
5. Assign each table or group of desks, a particular number of Expert Group. (Expert Group 1,
2, 3, 4, 5, and 6).
6. Ask each group to disperse and proceed to their assigned expert group number. (Student 1
will proceed to Expert Group 1, student 2 will go to Expert Group 2 . . . )
7. Distribute the copies of Expert Group cards accordingly. All students in each expert group
should receive the same card to read and discuss.
8. Allow them to read and discuss the content of the card for about 15 to 20 minutes. While
they are doing this, they will be considered experts of their assigned topic.
9. After discussion, ask them to return to their home groups.
10. In their home groups, ask each member to share what they have learned from their
respective expert groups to everyone in their home group.
11. Once everyone has shared the information, ask the following facilitation questions to solicit
a class discussion.
Facilitation Questions:
1.
2.
3.
4.
What is the difference between stratospheric ozone and tropospheric ozone?
Is tropospheric ozone a concern in the city of Houston? Why?
What are the ingredients in the formation of tropospheric or low-level ozone?
How do Nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs) contribute to the
formation of tropospheric ozone?
5. What are the weather conditions or meteorological factors that have some influence on
ozone formation?
6. How does each weather condition or meteorological factor affect ozone formation?
7. What are some effects of tropospheric ozone to humans and plants?
ELABORATE PART I
Teacher Notes: The elaborate activity is an inquiry lab where students formulate a hypothesis
from the different meteorological factors they have measured in the previous lesson. They need to
correlate these factors to the amount of tropospheric ozone. Students are asked to design their own
experiment to test their hypothesis. A complete lab report and presentation of results are required as
products for this activity. Important! It is imperative that students need to be reminded of the GLOBE
Protocols for each meteorological factor investigated.
Teacher Preparation: Make copies of the student materials namely; SM-3, SM-4 and SM-6 for
each group.
Materials:





Lab Worksheet (SM-3)
Cloud Guide (SM-4)
Ozone strips
Ozone scanner
Ozone and Meteorology Data Sheet
(SM-6)




Hygro-thermometer
Wind vane
Thermal glove
Infrared thermometer
Procedure:
1. Group students into at most four (4) per group.
2. Distribute the SM-3, SM-4, and SM-6 to each group.
3. Ask them to brainstorm for their own investigation.
4. Once they have the ideas, ask them to complete page 1 of the lab worksheet. For the
experimental site, it is preferable that they will choose their own site relevant to them such
as: certain location in their neighborhood or in the school, etc.
5. Instruct them that their experimental design should be reviewed and approved before the
end of the class period.
6. Remind students that they need to find their own time to collect data since this may take up
to 5 days to collect enough data. Planning and cooperation from each other are very
important for the success of the investigation.
7. Collect their lab reports during the scheduled presentation.
8. Ask them to prepare a Powerpoint for their presentation
ELABORATE PART II
Teacher Notes: In this online activity, students will see the fluctuations of tropospheric ozone
level in a particular area over a long period of time. They will also graph and interpret data using the Air
Quality Index (AQI) for ozone. This can be an option after the students design their own experiment since
they have to gather data on their own time.
Materials:
 Computers
 Graphing papers (SM-5)
 Pencils/color pencils
Procedure:
1.
2.
3.
4.
5.
Have students work individually or in pairs (depending on the number of available computers).
Instruct them to go to: http://www.tceq.texas.gov/agency/data/ozone_data.html
Let them click “The Daily Maximum Eight-Hour Ozone Averages.”
Allow them to pick a location of their own, such as the monitor closest to their home or school.
Ask them to graph the ozone levels of a certain area for a 1-month period. They can select the
month that interests them.
6. After graphing, ask them to interpret the data using the AQI for ozone and answer the
questions. Use Student Material 6 (SM-6) for the template.
Facilitation Questions:
1.
2.
3.
4.
Do you see any variation of the ozone level in the area you selected?
Which date has the highest ozone level? _______ Which one has the lowest? ________
Explain the possible cause or causes of this variation.
What should you do before going out for any outdoor activity?
EVALUATE
Teacher Notes: An essay is used as an evaluation tool for this topic. In the essay, students will
reflect and express their responsibilities on how they can participate in reducing the concentration of
tropospheric or low-level ozone in our area.
Teacher Preparation: Print copies of SM-5 for individual students or write the prompt on the
board. Students can use their own paper.
Procedure:
1.
2.
3.
4.
Distribute SM-5 or ask students to take out a sheet of paper.
Ask students to read the prompt.
Give them 20 minutes to write their essay.
Collect all essays for evaluation.