|
Lesson 5: Chemical Analysis of Water |
|
|
Lesson 5: Chemical Analysis of Water * A water analysis lesson about water chemistry and water quality Geared toward 3rd through 6th grade (targeted 4th grade) Materials o 1 Low cost GREEN Water Monitoring kit from LaMotte per 2 students + 1 for demonstration o 1 color card per 2 students plus one for demo o Test station set-ups for each test. Each test station includes one of the GREEN Water Monitoring kit’s white plastic canister taped to a stake and labeled with the test who’s supplies it will hold with laminated copies of the test’s instructions, test tubes and tablets. o Nitrile gloves in various sizes (Latex gloves can set off serious allergies), enough for all participants o Safety goggles for all participants o Sterilized bucket(s), 2- 2.5 gal with long rope tied to handle to gather stream water, with a cap if transporting (can be sterilized by boiling or cleaning and then rinsing with boiling water) o Waste water bucket o Trash receptacle for dropped tablets, aluminum foil wrappers and used gloves o Waders or water proof boots for the person collecting water if the water is to be used off site o One low cost GREEN water monitoring kit instruction booklet Activities o Set up supplies for the test, either placing what each student team will need for all the tests in the supplied white, plastic canisters or using the staked, labeled and pre-filled test station set-ups. o Discuss possible sources of impact on the streams and how they might impact streams (people, tree coverage or lack there-of, animal activity, etc.) and/or the needs of the fish and other living things in the streams. o Demonstrate for the students the correct method for getting the tablets out of the wrappers and into the test tubes (WSWCD staff can demonstrate), reading the thermometers (pg. 28) and reading the secchi disk. Make sure the students do the Dissolved oxygen first, unless you want them to discover what happens if you wait, then have at least one student group do them first and keep track of how long after the sample water was collected from the stream each D.O. test was done.. Instruct them to shake their water up before doing the Turbidity test (shaking will alter the Dissolved Oxygen test). Stress that they do NOT shake the Coliform test tube after adding water, just stand it upright. o Collect stream water § On-site testing – while maintaining grip on the rope, toss bucket out upstream and pull it back towards you, lift out of water before the bucket reaches shore, (WSWCD staff can demonstrate) § Off-site testing (transporting water to class room to test) refer to directions in the accompanying booklet, pg. 9. o Have students follow the easy to follow directions provided for each test and match the resulting colors to the accompanying color charts to find their test results (test tubes must be held up to the white area to compare colors. If accurate D.O. readings are desired, do this test first. Temperature should be done 2nd. o Students can grade their stream using the “ranking test results” starting on page 32 of the manual or using a table we can provide. They can do this for individual group results and/or class results. If class and group results differ, they can discuss why they think that happens. Have students discuss what the results mean and, if results were not acceptable, what might be done to fix the problem? o Notes of special interest – § As temperature increases, water’s ability to hold dissolved oxygen decreases and organisms demand for oxygen increases. § As nitrates/phosphates increase, algae increases, potentially blooming, so algae population is high enough to use up all the oxygen in the water each night . § pH range for salmon and most other aquatic life is 6.5 to 8.5 § Upper temperature limit for salmon is 13 oC for spawning, egg and fry incubation and 15oC for salmon rearing and migration Mat-Su District 4th Grade Science Standards addressed with this activity: o A1.1 Asking questions, predicting, observing, describing, measuring, making generalizations, inferring o A1.1a Working collaboratively, carrying out investigations o A1.1b Differentiating observation from inference and knowing scientists’ explanations come partly from what they observe and how they interpret their observations. o A1.1c Working with an increasing variety of models and tools. o A1.2a Formulating and justifying predictions based on cause and effect relationships Time Required o 10 minutes to set-up stations o Per test: § Dissolved oxygen (D.O.) – 12 min. (5 just waiting) § Temperature – 2 min. § Turbidity – 2 min. § pH – 4 min. § coliform – 2 min. to mix, incubate 48 hrs § Nitrates – 9 min. (5 just waiting) § Phophates – 9 min. (5 just waiting) § BOD (pg. 21) – 5 day incubation, 12 min. D.O. test § % saturation of dissolved oxygen – 14 min (12 min D.O. test + 2 min. using chart on page.19) o 20 minutes to clean up |
