2.5 Hour Lesson Grades 8-12
Co-written by Amanda Fisher and Mathew Lippincott
Description: In this lesson, students will use the skills learned in the first 3 lessons to monitor the health of plantlife in the world around them. This is intended to be the fourth lesson in the series of four.
Topics: photography, environmental analysis, biology, botany
|Introduction||Large group discussion||5 min|
|Photograph Beans||Large group inquiry activity and reflection||30 min|
|Leaf Chromatography||Small group exploration and personal reflection||30 min|
|Environment Photos||Small group exploration||45 min|
|Presentations||Small group presentations||25 min|
|Wrap-Up||Large group discussion||15 min|
Students will understand:
how tools can use ratios of absorbed and reflected light waves to capture environmental information
how quantitative and qualitative data can be synthesized to provide comprehensive observational information
how remote sensing can be used to evaluate ecosystem health
Students will be able to:
use ratios to describe relationships
synthesize information from multiple media types and multiple hands-on experiments
construct an enhanced tool
|Camera with removed IR filter||1/group or 1/class||from Lesson 3|
|Computer with internet access||1/group|
|small cups or jars||2/group||can be plastic or glass|
|rubbing alcohol or nail polish remover||1 bottle||99% alcohol or denatured alcohol are ideal|
|paper towels||1 roll||must be white|
|Bean Plants||2/student||From Lesson 1|
|red filter||1/group||From Lesson 2 and 3|
|red paper||1/group||From Lesson 3|
|popsicle stick, spoon, or similar||2/group||for stirring|
|Scotch Tape||4 pieces/ group||for labeling jars, and taping chromatogram to pencil|
|Tray with planting soil||1/group||for temporarily planting beans|
Cut paper towels into strips approximately 1” wide and 1-2” taller than the height of the cups or jars you will be using for the chromatography activity.
Observe areas around the school building that may be appropriate for Environment Photos activity.
Review Lessons 1-3.
Begin class by going over classroom expectations.
Ask students to write down a synopsis of the major points learned in Lesson 1, 2, and 3. As a class, briefly review the important role of wetlands and how they’re being destroyed, as well as how NIR photography can be used to assess the health of plants. You may need to remind students how to take NDVI photographs and analyze them in infragram sandbox.
Lesson 4 will tie together lessons 1, 2, and 3 by teaching students how the techniques learned in lessons 2 and 3 are used to monitor the health of wetlands, addressing issues raised in lesson 1. Students will engage in actual environmental monitoring in this lesson.
Arrange students into groups with one modified digital camera for each group.
Materials per group
- Digital Camera with IR filter removed
- Red filter
- Red paper
- Healthy and unhealthy bean plants from Lessons 1 and 3
Using the techniques used in Lesson 3, students will photograph the bean plants they have been growing. They will analyze these photos using infragram sandbox and see if they can tell healthy bean plants from unhealthy plants.
Invite students to decide how they would like to arrange the bean plants. They can put all healthy plants on one side and unhealthy on the other, or they can mix them up. Make sure they are arranged in a pattern or in a way that will allow students to identify which plants are healthy/unhealthy. This can be done within their groups, or could be done as a whole class with all bean plants together.
After the plants have been arranged, remind students the process for taking NDVI photos:
- Holding the red filter over the lens, white balance the camera by pointing it at a red piece of paper
- Photograph the plants while still holding the red filter over the lens. If possible, try to take the photo from above the plants to simulate an aerial photo
- Upload the photo into infragram sandbox
- Choose the “colorized” button next to “NDVI for red filter”
In small groups, discuss these questions and write brief answers to each: Compare the healthy and unhealthy plants. How do they look similar or different with your naked eye, and how do they look similar or different in the NDVI photos? How could you tell if an unknown plant is healthy or unhealthy by looking at NDVI photos of it?
Although our eyes can often do as good of a job telling healthy plants from unhealthy, we can only do this on a small scale, close up level. In order to get a big-picture view of how an entire ecosystem’s health, we need a tool like NDVI. It allows us to take aerial photographs of large areas of plants and gather information that we could not assess from normal visible light photography.
Think of a real-world question that could be addressed using NDVI aerial photography. Describe your question and your potential findings.
For this activity, arrange students in small groups of 2-4 students.
Materials per group
- 2 small cups or jars
- rubbing alcohol or nail polish remover (enough to fill cup about ¼”)
- 2 paper towel strips (about 1” wide by 4-5” tall)
- scotch tape
- popsicle stick or similar to stir with
In this activity, we will be taking a closer look at the pigments inside a leaf that are reflecting or absorbing light. We will see how these pigments differ in healthy and unhealthy plants. In one cup you will be testing your healthy bean plants. In the second cup, you will be testing your unhealthy bean plants.
- Using a permanent marker, or tape and a pencil, label the cups “#1- healthy” and “#2- unhealthy”.
- Tear up leaves from 1-2 of the healthiest bean plants into small pieces and place them into cup #1.
- Tear up leave from 1-2 of the unhealthiest bean plants into small pieces and place them into cup #2.
- Pour just enough rubbing alcohol or nail polish remover into each cup to barely cover the leaves.
- Stir the solution for a minimum of 5 minutes, smashing the leaves as you stir.
- Wait for approximately 15 minutes for the pigments to come out into your solution. During this time, review the directions for the photographing and presentation activities below.
- After the solution has turned green, you will place a strip of paper towel into each cup so that only the bottom edge of the towel touches the liquid. Tape the top of the paper towel to a pencil or pen, then lay it across the top of the cup (see image below).
- Observe as pigments move up the strip and spread out. It may take a few minutes to see the different pigments. For best results, leave the strips as you move onto the next activity, and check them again at the end of class.
Chromatography set up.
Paper towel strip.
There are four pigments you may observe in your experiment (although everyone may not have all four). The yellow-green chlorophyll B will be lowest on the strip, followed by the blue-green chlorophyll A right above it. Above that is the yellow xanthophylls, and at the top the orange carotenoids.
In small groups, discuss the following questions:
Why do you think plants have so many pigments? Different colored pigments can absorb different colors of light. This allows a plant to absorb more light which can be used as energy for photosynthesis.
Which pigments give plants their green color? Chlorophyll A is the main pigment found in green leaves. Its primary purpose is to convert light energy into chemical energy. Chlorophyll A is such a dominant pigment that we can not see the carotenes and xanthophylls in healthy leaves even though they are present. In the fall, chlorophyll begins to break down, allowing the carotenes and xanthophylls to show through with their orange, yellow, and red colors.
What differences do you notice in the chlorophyll amounts in healthy versus unhealthy plants? Students should observe a thicker band of chlorophyll in the healthy plants than in the unhealthy plants.
Individually, ask students to write answers to the following questions:
How does the chlorophyll-specific information compare to your visual assessment of the plants? Compare your chlorophyll information with your calculated NDVI values. Do you see any trends? If so, what are the trends and why? Thicker chlorophyll bands should correspond to higher NDVI calculated by infragram sandbox as the unhealthy plants will have less chlorophyll to reflect NIR and absorb visible light.
Arrange students into groups with one modified digital camera (from Lesson 3) for each group.
Materials per group
- Camera with IR filter removed
- Red filter
- Red paper
Now that we know how to identify the health of plants using NDVI photos, each group will choose an area around the school to take pictures and analyze plant health. Look for an area with lots of plants (grass, trees, or shrubs) and try to capture a large area in your photo. Where possible, simulate an aerial photo by taking pictures from a hillside, on top of playground equipment, or from a distance. Remember to use the red filter and white balance in order to separate the NIR channel from the visible light channel. Take a few photos so that you can choose the best after analyzing each photo in Infragram sandbox.
If time allows, students may take photos of more than one area. After returning to the room, allow students time to upload and analyze each photo in Infragram sandbox.
For this activity, students will remain in the same groups.
Each group will give a short presentation to the class about the results of their plant study. Thing to cover in your presentation include:
- Show NDVI photograph of beans from first activity and discuss which plants were healthy and unhealthy
- What outside area did you photograph?
- The resulting NDVI photograph
- An explanation of the results. What areas looked healthy or unhealthy?
- What changes would you expect to find in a different season?
- Was there anything surprising that you noticed in your photos?
Let students guide the discussion about the day’s lesson and present their hypotheses before discussing explanations.
Why are wetlands important?
Why do we need ways to observe the health of the wetlands, and how can we do it?
How is NDVI useful for analyzing plant health?
What is the most important thing you can take away from our four lessons together?
http://www.hsu.edu/pictures.aspx?id=1653 One example of the chromatography experiment (uses a slightly different procedure).
Chromatography: A process used to separate a mixture into its components.