Grade 8 Nelson Science & Technology Perspectives
Unit D: Water Systems
11.3 Testing Water Quality (pp. 296-297)
Vocabulary Concept Wheels
 BEFORE READING Section 11.3, brainstorm words or ideas in the "What I think it means..." boxes
for each of the vocabulary words.
 Read Section 11.3 pp. 296-297. As you encounter a vocabulary word highlighted in yellow, read the
definition in the margin. Can you rewrite the definition in your own words? Write the vocabulary word
and your own definition in the correct sections of the circles.
 List some examples for each vocabulary word.
 Draw an illustration that would help you remember the word and its definition.
1a) Turbid (p. 296)
Word
What I think it means...
Picture
Definition in
my own
words
Example(s)
1b) Thermal Pollution (p. 296)
Word
What I think it means...
Picture
Definition in
my own
words
Example(s)
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Explore and Explain
2. Using the chart below, summarize the material in this section.
Water Quality
Water Quality Indicators
Tools and Techniques Used to
Assess Each Indicator
2
Values or Characteristics that
Indicate Good Water Quality
Values or Characteristics that
Indicate Poor Water Quality
3. Fill in the chart below to explain how each of the following substances could enter a
freshwater source:
Substance
How It Could Enter a Freshwater Source
chlorine
nitrates
calcium
acid
4. Why do scientists use tools to measure water quality?
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5. Could a single water quality test provide a definitive answer about whether a water sample
is of good quality? Explain why or why not.
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6. Look at Figure 1 on p. 296. Why do you think a Secchi disk is two-coloured?
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7. A decrease in oxygen levels is not the only problem associated with thermal pollution.
Some organisms require specific water temperatures in order to breed or grow, so thermal
pollution can harm them, even if the dissolved oxygen levels in the water remain high.
Alternatively, warming water can benefit some organisms, such as algae, which in turn may
grow rapidly. This leads to other water quality problems. In addition, warm water is better
able to dissolve certain contaminants, so thermal pollution may increase chemical
contamination of a water body. Finally, the circulation of many water bodies (which helps
dissolve oxygen in the water and bring nutrients from deeper water into shallow water for
organisms to use) depends primarily on temperature differences. Discharging warm water
into water bodies can interrupt the circulation of these water bodies and harm their
ecosystem.
Based on this information, is there a specific temperature range that is considered ideal for
all water bodies? Explain why or why not.
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