Worksheet Grade 9 English Language Arts
Precise Units in a Heron Pond Pollution Notice: Grade 9 Worksheet
A grade 9 technical writing worksheet where students convert pollution readings between ppm, mg/L, and percent, then revise a fictional pond notice for clarity.
Objectives
- Students will convert water-quality measurements between ppm, mg/L, and percent concentration using given conversion relationships.
- Students will revise vague or inconsistent unit usage into precise, audience-appropriate technical writing.
- Students will explain why consistent, precise units matter in a public health notice.
Vocabulary
- Parts per million (ppm)
- Parts per million tells how many tiny bits of a substance are mixed into a million bits of water. Scientists use it to measure very small amounts of chemicals in water.
- Dissolved oxygen
- Dissolved oxygen is the oxygen gas mixed into water that fish and other underwater animals breathe. Cold, moving water holds more oxygen than warm, still water.
Also: concentration, nutrient pollution
Teacher overview
A neighborhood group drafting a public notice about pond pollution has to translate lab numbers into sentences that any resident can understand, and mixing units without converting between them is one of the most common ways that effort goes wrong. This worksheet has students convert pollution readings between ppm, mg/L, and percent concentration, then revise a draft notice so its units stay consistent. A common misconception this worksheet addresses is treating percent, ppm, and mg/L as if they described different quantities; the conversions in items 1 through 6 are built to show that, in fresh water, they are simply different ways of expressing the same concentration.
Student Worksheet
The Heron Pond Neighborhood Watch, a fictional community group, is drafting a public notice about pollution readings from Heron Pond after heavy rain washed fertilizer off nearby lawns. Use these two facts for the conversion items: in fresh water such as pond water, 1 mg/L is approximately equal to 1 ppm, and a 1 percent solution equals 10,000 mg/L.
The draft notice states a nitrate reading of 8 ppm. Convert this reading to mg/L.
A second sample read 12 mg/L of nitrate. Convert this reading to ppm.
A lab result described one runoff sample as "a 0.02 percent nitrogen solution." Convert this concentration to mg/L.
A separate sample read 450 mg/L of dissolved solids. Convert this reading to a percent concentration.
Dissolved oxygen in the pond measured 3 mg/L. Convert this reading to ppm, and state whether it meets or falls short of the 5 mg/L that most fish need.
A second runoff sample, collected at a different storm drain, measured "0.008 percent nitrogen." Convert this concentration to mg/L.
The draft notice includes this sentence: "It has been determined that fertilizer is the likely source of the nitrogen." Identify the passive-voice construction and rewrite the sentence in active voice, naming "the Watch's testing team" as the one who determined this.
The draft notice includes these two short sentences: "Nitrogen feeds algae growth. When the algae die, their decay uses up oxygen fish need." Combine them into one clear sentence using a connecting word such as "because" or "which."
A reader asks the Watch why the notice reports both ppm and mg/L instead of picking one unit. Draft a one-sentence explanation a Watch member could give.
Explain why a public notice about pond conditions should state exact numbers with clear, consistent units, rather than words like "somewhat elevated" or "not great," especially when neighbors will decide whether to let children swim or fish there.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: 8 mg/L. Because 1 mg/L is approximately equal to 1 ppm in fresh water, an 8 ppm reading is essentially the same concentration as 8 mg/L.
- Answer: 12 ppm. The same reasoning applies in reverse: in fresh water, 12 mg/L is about 12 ppm.
- Answer: 200 mg/L. 0.02 percent × 10,000 mg/L per 1 percent = 200 mg/L.
- Answer: 0.045 percent. 450 mg/L ÷ 10,000 mg/L per 1 percent = 0.045 percent.
- Answer: 3 ppm. This is below the 5 mg/L most fish need, so a reading of 3 mg/L (3 ppm) suggests fish in the pond could be under stress.
- Answer: 80 mg/L. 0.008 percent × 10,000 mg/L per 1 percent = 80 mg/L.
- Answer: The passive construction is "It has been determined that...". A correct active revision is: "The Watch's testing team determined that fertilizer is the likely source of the nitrogen."
- Answer: Accept any combined sentence using a connecting word, for example: "Nitrogen feeds algae growth, and when the algae die, their decay uses up oxygen fish need."
- Answer: Accept reasoned answers, for example: "We report both units because some readers are more familiar with one term than the other, and in fresh water like the pond's the two numbers are nearly identical."
- Answer: Accept reasoned answers. A strong response explains that vague words cannot be compared to a benchmark like the 5 mg/L fish need, while exact numbers with consistent units let a reader judge the actual risk and make an informed decision about the pond.
Differentiation
Support (below grade level)
Provide the two conversion facts as a labeled reference card ("ppm to mg/L in fresh water: same number" and "percent to mg/L: multiply by 10,000") and allow a calculator for every conversion item. Reduce items 9 and 10 to short spoken responses.
Extension (above grade level)
Ask students to draft one additional sentence for the notice that reports a new hypothetical reading using percent, then trade with a partner and have the partner convert it to mg/L and ppm.
ELL supports
Pre-teach "concentration," "convert," "consistent," and "benchmark" with simple definitions and a visual showing the same amount of a substance labeled three different ways. Allow items 7 and 8 to be completed using sentence-combining cards instead of writing from scratch.