Introduction
Hello all! You drink, bathe and even wash your dishes and clothes in clean water. You don't use water alone for washing in many instances but mix soap, shampoo, detergent etc. as the cleaning substances are available in plenty which tend to make the cleaning act more convenient and pleasurable. Have you ever thought of the chemical substances that get pushed into your water drains after washing your hair with shampoo, bathroom sink using bleach? Studying this lesson will help you understand the difference between healthy and unhealthy water, and dirty and polluted water that is caused as a result of substance use.
Task
In this lesson, you will get to listen to the story “A girl and Water”. After listening, lets brain storm our ideas and understanding together about the substances that cause the water to get dirty or polluted. You will then conduct an experiment by adding few test substances to clean-water sample, and figure out whether it causes to be dirty or pollute. Then we wind down towards microscopic observation of water brought from the Tule ponds field trip. Finally, you will get to look at five different water samples through the microscope and write down from the made observations whether each water sample is dirty or polluted considering the potential impact to the organisms and environment under use.
Process
I Storybook
Let us read a story book together.
II Brainstorm
Each table has been given two empty index cards and pencils to create two kinds of lists. One of the index card should contain a list of Pollutants and the other a list of Dirty components that could be present in water. Please discuss within your group and write down the list. You are given five minutes to complete this activity.
Let us take turns among each table to read aloud one component at a time from the pollutant list.
Let us take turns among each table to read aloud one component at a time from the dirty component list.
III An experiment to differentiate between polluted and dirty water
IV Observe water sample from Tule ponds through microscope
Microscopes have been set at the back table. Each of you will work with a partner. Here is the process to observe microscopic-life from the pond if present any. The following materials have been supplied on the table:
- Glass microscope slides
- Plastic cover slips
- Paper towels or tissues
- Samples of water from Tule ponds
- Plastic pipette or dropper
Follow the below method.
- Place a drop of pond water on a microscope slide with a pipette or dropper.
- Place a coverslip on top (optional) and observe.
We have made observations here in the science laboratory using the same microscopes. Hence I assume that you are familiar with the process. Be aware of the sensitivity of the moving rod. I can help those of you who have trouble with getting the lens close to focus.
Those who are lucky and found many microscopic life may want to make further observations. We have a multi jar samples of the following.
jar 1 = 1/4 water + soil
jar 2 = 1/4 water + 2 drops of food coloring
jar 3 = 1/4 water + 3 drops of oil
jar 4 = 1/4 water + 3 drops of soap
jar 5 = 1/4 water + salt
You may follow the same observation method by pipetting out water from them one jar at a time.
Evaluation
Students should figure out if the water is polluted or dirty and record the observations on the sheet. Use the microscope to look at a drop of each of the water to see if students can identify particles in the water. You must remember that polluted or dirty water sometimes depends on the type of animal using that water. What may not be toxic to humans, may be toxic to little animals, or vice versa. For instance, soap in water is not polluted if we wash our face, but if we had to drink soapy water it would be polluted.
Justify your answers.
| Water Source | Look at Naked Eye | Look Under Microscope | Life Guess | Dirty / Polluted | Reason |
|---|---|---|---|---|---|
| Tule Ponds | |||||
| Jar 1 | |||||
| Jar 2 | |||||
| Jar 3 | |||||
| Jar 4 | |||||
| Jar 5 | |||||
Conclusion
Let us recap all the scientific vocabulary that was part of the lesson.
If today's science lesson be summarized, lets hear from you how it would be.
Table 1, What is today's topic?
Yes, its mainly about the dirt and pollution present in the water.
Table 2, What could cause a water to be dirty?
Yes, mud, poop etc.
Table 3, What could cause a water to be polluted?
Yes, chemical waste, plastic etc. and the list is endless
Table 4, Did we identify any toxic substances or disease causing organisms in water through the microscope?
Table 5, What is the lesson take away?
Credits
The lesson corresponds to the following Next Generation Science Standards (NGSS).
PS-1-3 Matter
https://www.nextgenscience.org/dci-arrangement/ms-ps1-matter-and-its-interactions
ESS 2–2 Water, ESS 3.C Human Impacts on Earth Systems
https://www.nextgenscience.org/dci-arrangement/ms-ess2-earths-systems
Teacher Page
Water is an important resource for all people in the world. People can die from lack of clean water to drink. Most students do not think about water because in the United States it is almost an unwritten rule that cities, counties, states and the federal government will provide this resource. Early in our country this was not so. Many people died because the rain did not bring water or that sewage from a city polluted the waterways. The United States is aware o
f the dangers of polluted water and have one of the strictest laws in the world. Not all nations in this world have water privileges that Americans have.
The world’s oceans have always been a “dumping” ground for pollution. In many areas raw sewage and other wastes are put into the oceans. Many humans see the oceans as such a vast place that it could never get polluted. But this is wrong. Currents in the oceans move the pollution away from the land, but it still remains in the system. Some wastes are sometimes used by plants and animals in the oceans to help them grow, but too much will upset the natural balance.
There are some substances that will dissolve and others that will remain in the system. For instance, plastic will not degrade and remains floating on the world’s oceans. Other substances like phosphorous (from soaps) can be used by small plants in the oceans as fertilizer.
Pollution is a term used by the media and general public frequently. However, most children do not understand how the word differs from dirty. Pollution is when water (or any other part of the environment) becomes offensive or harmful to organisms. Fresh and salt water can become polluted. However, seawater is not polluted just because it is salty.
Salt water, although not useful to drink by humans, is not polluted or dirty; it has mineral salts dissolved in it. This lab has the students think about the difference between dirty, polluted, and clean water.