Principles:
Facts:
- Some materials like salt or vinegar are non-toxic if they are mixed into water in very small
amounts
- Many materials that get into water can be harmful.
Skills:
- Following Directions
- Understanding Cause-and-Effect Relationships
- Making Inferences
- Drawing Conclusions
Materials:
- Two cups of water
- Small pile of table salt
- One cup of vinegar
- Teaspoon
- Handout
Room Preparation:
Students need tabletop space, elbow room, access to water and clean-up
materials.
Safety Precautions:
Water, salt, and vinegar may spill. Avoid getting vinegar or salt in eyes.
Procedures and Activities
Introduction
- Is the water we drink safe? How can we tell if it is safe or not? What
materials are 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.
Activity
- Give each pair or small group their materials and handout.
- Go over the roles needed:
- Someone to be "polluter" (to put in teaspoons of salt or vinegar and
to stir the water).
- Someone to be "taster" (to determine when they detect pollutants and
when there is too much to drink safely).
- Someone to be "recorder" (to write down the number of teaspoons of
salt and vinegar added, the taster's descriptions of taste, and when
it is too much).
- Explain the experiment process. First add one teaspoon of salt at a time
to one cup of water. Stir each time, taste, and document what is seen and
how it tastes on the hand-out. Stop when it tastes too bad to drink.
Repeat the process with new glass of water and vinegar.
- 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 health problems, yet
sometimes we don't know that what we are drinking is harmful to us.
Closing - Original Question
Ask again: "Can our taste buds and eyes detect unsafe drinking
water?"
Evaluation
During class discussion, note if students understand concepts of drinking
water, ground water, and the principles of pollution or contamination, and
conclude that we often cannot tell by taste or observation what is in our
water or if it is safe to drink. Students may make oral or written
presentations to share their experiment, observations, and findings.
Extension Ideas
- Draw a bar graph comparing the amounts of salt and vinegar different
"tasters" found to be undrinkable. Talk about our individual taste bud
differences and that taste is not a reliable indicator of harm.
- Have students research table salt and other chlorides (like road salt)
to learn more about this seemingly harmless substance. Students may talk
to nurses, doctors, people with heart and blood pressure problems,
dieticians, road commissioners, environmentalists, and natural resource
specialists. Students can share findings by oral presentation or written
report. Students will see the profound impact something like salt can
have on us and on our ground water.
- Have students think about what they can do to clean and preserve the
earth. Encourage students to put their ideas to use. To get started,
review 20 things we can do to help
reduce pollution and preserve our Earth.
- Plan an environmental field trip:
- Explore the wealth of data collected by the federal government, such as
the National Hydrography Dataset, or
the U.S. Environmental Protection Agency's Surf Your Watershed, or
other information available through the U.S. Geological Survey.
Careers Related to the Lesson Topic
Prerequisite Vocabulary
- Contaminated Water
- Water that has become mixed with a poison or another material that
may—if there is enough of it—be dangerous to those who drink
or use it
- Drinking Water
- Water (usually from under the ground or on the surface, as in lakes or
rivers) that we use for cooking, drinking, washing, and so forth
- Groundwater
- Water that sinks into the earth and supplies wells and springs
- Non-Toxic
- Not poisonous
- Toxic
- Poisonous
- Toxins
- Harmful and poisonous materials or substances
Lesson provided by Ecology Center, 734-995-5888, 117 N.
Division St., Ann Arbor, MI 48104
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