 |
 |
 |
 |
|||||||
 |
||||||||||
|
||||||||||
|
TIME ALLOTMENT:
Introductory Activity: 30 minutes Learning Activity: 50 minutes Optional Hands-on Activity: 30 minutes every other day for approximately 1 - 2 weeks Culminating Activity: 50 minutes OVERVIEW: SUBJECT MATTER: Environmental Science LEARNING OBJECTIVES: STANDARDS: Louisiana Science Frameworks: MEDIA COMPONENT: Water Pollution http://edugreen.teri.res.in/explore/water/pollu.htm This Web site provides information about the various sources of water pollution, how algae blooms occur, and what effects algae blooms have on organisms living in the water body. MATERIALS: Optional Hands-on Activity PREP FOR TEACHERS: 3. Make copies of handouts for two web search activities and answer keys. 4. Determine and assign group arrangements for students. 5. Prepare a large sheet of bulletin board paper for suggestions or use chalkboard. 6. Copy the e-mail response sheet for the culminating activity. 7. Make color copies of the aquarium page (Activity Sheet 1) for use by students or make a color transparency of each. 8. When using media, provide students with a Focus for Media Interaction, a specific task to complete and/or information to identify during or after viewing of video segments, Web sites, or other multimedia elements. INTRODUCTORY ACTIVITY: 2. Have students look at the pictures of a crystal clear fish tank and the same one that is cloudy or filled with algae. Ask them what differences they notice between the two pictures. Ask students if they have ever seen a fish tank that is cloudy and full of algae? 3. Ask students, “Was the algae something bought and placed in the tank when it was being set up? If not, how did it get in the tank? What caused the cloudiness?” (The cloudiness is from bacterial growth that occurs when you have a lot of decomposition going on in the tank. The algae spores are always present in the water, but are dependent upon nutrients for their growth. Algae growing in the tank contribute to the cloudiness, also.) 4. Ask, “What could have happened to increase the amount of algae that was present in the water to the level that it could be easily seen?” (Students may respond that the algae reproduced and grew because they found the nutrients they needed in the water supply.) 5. Ask, “Where did the nutrients come from? Did the person that set up the fish tank add nutrients on purpose? If not, how did they get into the water supply?” (Students may suggest that the nutrients are present in the food that is fed to the fish. Fish excretion also adds nutrients to the water. Animals and plants that die also decompose, providing the water with a new nutrient supply.) 6. Ask, “What happens to the excess food that is left after fish finish feeding?” (It sinks to the bottom of the tank and is decomposed by bacteria. The released nutrients are used by the algae to grow in numbers large enough to see with the naked eye. ) 7. Ask, “How does the excess algae affect the fish in the tank?” (The algae produce oxygen during the day, but at night they respire, using the oxygen in the water. This depletes the oxygen supply for the fish and eventually the fish die. 8. Ask students what they can do to eliminate the cloudiness and algae blooms found in their fish tanks? (Students with fish tanks may suggest: kill and remove the algae regularly from the tank, replace some of the water each week, reduce the amount of food being fed to the fish on a daily basis, reduce the amount of time the aquarium light is on). 9. Ask students, “Where else might this problem occur, besides in fish tanks?” (in bodies of water such as streams, lakes, rivers, the Gulf, and oceans—anywhere where excess nutrients can be deposited). 10. Ask, “Can we solve similar problems occurring in these water bodies the same way as we can with an aquarium?” (No, but we can recognize the source of the problem (excess nutrients) and try to reduce or eliminate it.) Have students suggest possible ways to reduce the problem in real water bodies. Record suggestions on the board or chart paper for future discussion. 11. Tell students that they will be learning more about the effects of excess nutrients in water bodies and how they affect the organisms living there. LEARNING ACTIVITIES: 2. Have students form groups to do web research. Provide students with a FOCUS FOR MEDIA INTERACTION, telling them to find out why algae becomes a problem in aquariums and how to prevent or eliminate algae growth in the tank. Provide students with Learning About Algae Web Worksheet to guide their search of the Web site: http://www.theaquarians.net/ArticlesandWallpapers/article_algae.htm. Review answers with students, emphasizing the effect of nutrients on algae growth. 3. Tell students that what happens in an aquarium can be viewed as a model of what happens in larger water bodies, such as ponds, rivers, lakes, the Gulf of Mexico, and even oceans. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them, “How do excess nutrients get into larger bodies of water and what problems do they cause? Provide students with Algae as Water Pollution Web Worksheet to guide their search of the Web site: http://edugreen.teri.res.in/explore/water/pollu.htm. Review answers with students, relating how nutrients in larger bodies of water cause algae blooms and affect the organisms living there in a similar way to what happens in aquariums. 4. Provide students with a FOCUS FOR MEDIA INTERACTION, telling them to view the video to understand how excess nutrients can cause algae to grow in a water body such as a river, lake, or stream. RESUME playing the video until you hear the words, “It might be fun to take a closer look. Let’s do a eutrophication magnification,” and see Greg Grandy turn toward the water with a magnifying glass. PAUSE the video, asking them: “How did the extra nutrients get into the pond in the video?” (Excess fertilizers from the nearby golf course mixed in with rain water and ended up in the pond through run off.) Ask students if their parents use fertilizer on their own lawns. Why? How can these fertilizers from their lawns get into a nearby water body? (When it rains or the lawn is watered, excess fertilizer is carried into storm drains and eventually dumped into a water body.) Remind students of what happened when excess nutrients were in the fish aquarium. Ask, “What do you think happens to organisms when extra nutrients in a pond, lake, river, or larger body of water cause algae blooms?” 5. Provide students with a FOCUS FOR MEDIA INTERACTION, telling them to view the video to find out what happens to fish and other organisms when too many nutrients enter a body of water. RESUME PLAY until you see fish turning upside down and floating at the top of the water and hear the words, “Once the oxygen level drops below a certain point, then the fish can no longer effectively breathe.” PAUSE the video and ask, “ What caused all of the fish to die? (low levels of dissolved oxygen). What caused the oxygen in the water to become depleted? (The excess nutrients created algae blooms. When the algae died, they sank to the bottom of the pond and were decomposed by bacteria and fungi. These organisms require oxygen to decompose the dead algae, thereby depleting the available oxygen in the water.) Remind students that the students at the beginning of the video were asking what was causing the cloudiness in the aquarium. Explain that the cloudiness was caused by bacteria, fungi, and other microorganisms that are decomposing the decaying algae. FAST FORWARD the video almost to the end, right after you hear the words, “The idea behind regulating nutrients and controlling their input into the bay is to improve the water quality which will reduce the amount of low oxygen bottom in the bay and open that bottom up for use by crabs and fish and other organisms all year round.” 6. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to view the end of the video to determine what these students learned about improving the water quality in their fish tank. RESUME PLAY with Greg Grady looking through the fish tank and right before he says, “We’ve learned that there is an important relationship between what goes in our water and the conditions that follow.” Ask students, “What is the relationship between what goes into our water and the conditions that follow?” Have students explain what they learned from the web search and the video. (Knowing about and controlling the nutrient levels that enter the water will help avoid the water becoming anoxic or hypoxic.) 7. Ask students, “Can we use any of the methods of removing algae from aquariums to help remove algae from larger bodies of water?” (Students should respond that decreasing the amount of nutrients entering the water is the only way to reduce the algae blooms because the other methods are already being done by nature or can’t be done with large water bodies. Ask students to suggest ways that nutrients entering water bodies can be reduced.) Refer students back to the suggestions they made in the Introductory Activity (Step #9). Compare their new suggestions with the ones made then to determine what they learned from the lesson. Optional Hands-on Activity—Studying
the Effects of Excess Nutrients on Dissolved Oxygen Levels
in Water 2. Place two clear tubs of pond water in front of class. Label one tub “No fertilizer added”, and the other “Fertilizer added.” Add 100 ml of Root Stimulator Fertilizer to the tub labeled “Fertilizer Added.” 3. Have a student take the beginning temperature of each tub of water. Have students record beginning temperature on chart. Have each group record visual observations of water clarity on chart. Place tubs in a sunny window and allow them to sit for 48 hours. (Time may need to be extended during cooler weather or cloudy conditions.) Part II 5. Remind students to wear gloves and collect a sample of the water with no added nutrients in the test tube. Direct them to place the test tube completely below the water and cap it while it is still under. There should be no air bubbles in the tube. Carefully uncap the bottle and add two Dissolved Oxygen TesTabs. Recap the bottle and shake it 3-4 minutes until the testabs dissolve. Once dissolved, set the bottle on the desk and allow it to sit for five minutes. Use the color chart provided with the D.O. test to determine the approximate amount of dissolved oxygen in the bottle. Record on the chart. 6. Pour out the water and rinse the bottle with distilled water. Repeat step six using the water with the added fertilizer. Record results on chart. Allow water to sit for 48 more hours and repeat temperature reading and dissolved oxygen tests. (Depending on the time of year that this lesson is being done, the algae may take longer to grow in the tubs. In late spring and summer, algae growth will be faster, however, in fall, winter, and early spring, it may take a week or longer for the algae to grow enough to show death, decomposition, and lowered dissolved oxygen amounts. Adjust the time needed to accommodate the season.) 7. Discuss the results with the class. They should notice that the tub with extra nutrients has more algae growth. The dissolved oxygen readings for the fertilized water should also be lower once the algae begin to die and decompose. (Due to the type of test used, students will not be able to get an exact reading of D.O., they should however, be able to see a difference in water color in the tube, which will indicate one has less oxygen than the other.) 8. Ask students if they noticed any differences in temperatures between the tub with no fertilizer and the tub with fertilizer. If there was a noticeable difference in temperature ask if they noticed any differences in the amount of algae growth when compared to temperature? Was there any difference in the amount of algae growth when compared to fertilizer amounts? Record students’ observations on wall chart. What generalizations can be made concerning nutrients and algae growth? (increased nutrients usually spur increased algae growth, less nutrients mean less algae growth) What generalizations can be made about temperature and algae growth? (the higher the temperature, the more algae growth you will see) 9. Relate what students learned in the Learning Activity to the results of the hands-on activity. Be sure to emphasize how the dissolved oxygen levels decreased after the algae started to die. CULMINATING ACTIVITIES: CROSS-CURRICULAR
EXTENSIONS: COMMUNITY CONNECTIONS: STUDENT MATERIALS:
|
•
LPB NTTI • Master
Teachers • Handheld Resources •
Lesson Plans • Professional
Development •
• LPB Interactive • National
NTTI •
