Contaminated DRINKING WATER Glenda Jennings
* This lesson was adapted from the Internet version offered at the University of Michigan Education site. It was provided by the Ecology Center, 117 N. Division St., Ann Arbor, Ml 48104, (303) 995-5888.Guiding Question: Can our taste buds and eyes detect unsafe drinking water?
IRP Learning Outcomes (Grade 4):
It is expected that students will...
* outline the importance of water for life.
* describe human impacts on the Earth's water resources.
Concepts:
* Drinking water is an essential part of everyday life.
* Groundwater supplies many places with drinking water.
Principles:
* Contaminated water is the result of toxins mixing with the drinking
water.
* Water that looks safe may actually be toxic.
Facts:
* Some materials like salt or vinegar are non-toxic if they are mixed in
small amounts of water.
* Many poisons and materials that mix with and get into water can be very
harmful.
Materials:
For each pair of students you will need... two cups of water
small pile of table salt one cup of vinegar or vinegar packages teaspoon
handout
Procedures and Activities:
Introduction:
1. What are some of the ways in which we use water? How is water
important to our health?
2. Is the water we drink safe? How can we tell if it is safe or not safe?
What materials or substances are in our water?
3. Can we be sure as to what exactly is in our water?
Today, we will see if we can tell if our water is safe to drink by looking at it and tasting it.
* 4. Can our taste buds and eyes detect unsafe drinking water?
Activity:
1. Give each pair their materials and [handout].
2. Go over roles needed:
i) Someone to be "polluter" (put in teaspoons of salt and vinegar and stir into water).
ii) Someone to be "taster" (determine when they detect pollutants and when there is too much to drink safely).
iii) One of the two to also be the "recorder" (write down the number of teaspoons of salt and vinegar added, describe taste, note appearance, and note when there is too much).
3. Explain experiment process. First, they are to add one teaspoon of salt at a time to one cup of water. Stir each time, taste, and document what they see and how it tastes on the handout. Stop when it tastes too bad to drink. Repeat the process with a new glass of water and vinegar.
4. Ask if students know when there is too much salt or vinegar in the cup for their bodies to safely handle? Share that too much salt is very risky for people with blood pressure, heart or other problems. Sometimes we don't know that what we are drinking is harmful to us.
Closing:
Ask again: "Can our taste buds and eyes detect unsafe drinking water?"
Determine that it is sometimes very difficult to detect with our taste buds and eyes whether our drinking water is contaminated. This becomes increasingly dangerous when we consider how toxic materials could go undetected if we were to use only our eyes and taste buds to test our water.
This could lead into discussions regarding how groundwater pollution and contamination makes water treatment necessary prior to drinking. It could also serve as a lead-in to discussing the potential difficulties in testing water. Students could create a bar graph comparing the amounts of salt and vinegar different "tasters" found to be undrinkable. Students could determine that certain tests are therefore less reliable than others and could generate ideas for tests which might be more reliable (less subjective). This could be and inroad to examining pH levels and testing with Litmus Paper/Cabbage Juice.