HS-ESS3-4NGSS*ScienceEarth and Space ScienceGrades 9-12
HS-ESS3-4: Evaluating and Refining Solutions That Reduce Human Impacts
In plain English: HS-ESS3-4 is the NGSS high school performance expectation that asks students to evaluate or refine a technological solution that reduces the impacts of human activities on natural systems. Students judge a solution against criteria and constraints using data on pollutants, land use and species, then propose an improvement the data support. It is often taught in Earth and Space Science or Environmental Science.
Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.
Clarification Statement: Examples of data on the impacts of human activities could include the quantities and types of pollutants released, changes to biomass and species diversity, or areal changes in land surface use (such as for urban development, agriculture and livestock, or surface mining). Examples for limiting future impacts could range from local efforts (such as reducing, reusing, and recycling resources) to large-scale geoengineering design solutions (such as altering global temperatures by making large changes to the atmosphere or ocean).
Next Generation Science Standards · Disciplinary Core Idea: Earth and Human Activity · Official standard
Students evaluate and refine technological solutions that reduce the impact of human activities on natural systems. They set criteria (what a solution must achieve) and constraints (limits such as cost, land and water), use before-and-after data to compute percent reductions and cost per unit of benefit, look for trade-offs that move the impact somewhere else, and propose a refinement that the data support. The solutions range from a school cafeteria and a stormwater pond to a power-plant scrubber and model studies of geoengineering.
The NGSS Clarification Statement says: "Examples of data on the impacts of human activities could include the quantities and types of pollutants released, changes to biomass and species diversity, or areal changes in land surface use (such as for urban development, agriculture and livestock, or surface mining). Examples for limiting future impacts could range from local efforts (such as reducing, reusing, and recycling resources) to large-scale geoengineering design solutions (such as altering global temperatures by making large changes to the atmosphere or ocean)." This performance expectation has no separate Assessment Boundary. Every data set and model summary on this page is invented for teaching, with realistic sizes, and the page does not endorse any geoengineering plan: students evaluate what the model results show. Students do the practice of evaluating and refining a design solution: they compare data with criteria, weigh trade-offs and redesign.
Learning Objectives
By the end of this lesson, students will be able to:
Distinguish the criteria a solution must meet from the constraints it must work within
Use impact data (pollutant quantities, species diversity, biomass, land area) to compute percent reduction and cost per unit of benefit
Identify trade-offs, including impacts a solution moves to another part of a natural system
Evaluate local efforts and large-scale geoengineering proposals against the same criteria, using model results where no field data exist
Refine a solution by changing one design variable and showing with data that the refined design meets a criterion the original missed
Prior Knowledge Required
Students should already be comfortable with:
Designing a way to monitor and reduce a human impact on the environment MS-ESS3-3
Evaluating competing design solutions with a systematic process MS-ETS1-2
Percent change and unit rates 7.RP.A.3
The idea that pollution, land clearing and habitat loss affect living things in an ecosystem
Show a photo of a storm drain stenciled "Drains to Creek" next to a school parking lot. Ask students to answer on their own first, then compare with a partner.
Warm-Up Prompt
"The school wants to stop muddy, oily runoff from the parking lot from reaching the creek. Someone suggests a gravel trench at the edge of the lot. Before you decide whether it is a good solution, what would you want to measure, and what would count as success?"
List student ideas in two columns without labeling them yet: what the solution must achieve (cleaner water, less flooding) and the limits it must work within (cost, space, upkeep). At the end of Direct Instruction, label the columns criteria and constraints.
Direct Instruction15-20 minutes
Evaluating and refining with data. A solution is judged against criteria (measurable goals, such as removing at least 80% of sediment) within constraints (limits on cost, land, water, energy or time). Evaluation uses data: the percent reduction is (before - after) ÷ before × 100, and the cost per unit of benefit is the cost divided by the amount of pollutant removed or waste avoided. A good evaluation also asks where the impact went: a solution can remove one pollutant and create another, or save landfill space and use more water. To refine a solution, find the criterion it misses, change one design variable and show with new data that the change works. Use Diagram 2 to show the cycle, and Diagram 1 with the fifth example. All data in the examples below are invented for teaching, with realistic sizes.
Pollutant data: evaluating a scrubber
A coal-fired power plant released 18,000 t of sulfur dioxide (SO2) per year. After a wet limestone scrubber was installed, it released 1,080 t per year. The criterion is at least 90% removal. The scrubber reaction is SO2 + CaCO3 + ½O2 + 2H2O → CaSO4·2H2O + CO2 (molar masses 64, 100, 172 and 44 g/mol).
Result: Removed: 18,000 - 1,080 = 16,920 t, so removal = 16,920 ÷ 18,000 = 94%: the criterion is met. Trade-offs: the plant uses about 16,920 × 100/64 ≈ 26,400 t of limestone a year (a quarry is a land-use impact), makes about 45,500 t of gypsum (sold for wallboard if a buyer exists) and releases about 11,600 t of CO2 from the limestone.
Land use and species diversity: mine reclamation
A surface mine disturbed 640 ha. Eight years after reclamation began, 480 ha are regraded and replanted. Survey plots on reclaimed land average 18 plant species, and undisturbed reference plots nearby average 36. The permit requires at least 70% of the area revegetated and species richness at least 60% of the reference.
Result: Area: 480 ÷ 640 = 75%, so the area criterion is met. Diversity: 18 ÷ 36 = 50%, below 60%, so it is not met. A refinement the data support: salvage and replace the original topsoil, which holds native seeds, and plant a native seed mix; then survey again.
Local effort: reusable cafeteria trays (reduce and reuse)
A school cafeteria throws away 1,200 foam trays a day (9 g each) for 180 school days. Switching to washable trays means the dishwasher runs 48 extra racks a day at 3.5 L of water per rack.
Result: Waste avoided: 1,200 × 9 g = 10.8 kg a day, or 10.8 × 180 = 1,944 kg (about 1.9 t) a year. Water added: 48 × 3.5 = 168 L a day, or 30,240 L a year. The solution reduces landfill waste but moves part of the impact to water and energy use, so the energy per rack is the next data to collect.
Large-scale geoengineering: aerosol model results
An invented model summary for stratospheric aerosol injection: without it, the model warms 2.4 °C above preindustrial by 2080; with continuous injection, 1.5 °C. Atmospheric CO2 in the model keeps rising at the same rate. Rainfall in one monsoon region falls by 5%. If injection stops suddenly, the model warms back by 0.9 °C in about 15 years.
Result: Warming avoided: 2.4 - 1.5 = 0.9 °C, which is 0.9 ÷ 2.4 = 37.5% of the warming. The rebound rate after a sudden stop is 0.9 ÷ 15 = 0.06 °C per year (0.6 °C per decade), much faster than the warming it replaces. The approach meets a temperature criterion but fails criteria about rainfall, reversibility and the rising CO2.
Refining a stormwater pond
A stormwater pond receives 5,000 kg of suspended sediment a year and releases 2,000 kg to a creek (60% removal). The goal is at least 80% removal. Refinement 1 adds a vegetated forebay that traps 40% of the incoming sediment before the pond. Refinement 2 also adds a baffle that lengthens the flow path and raises the pond's own removal to 70%.
Result: Refinement 1: 5,000 × 0.60 = 3,000 kg reach the pond, and 3,000 × 0.40 = 1,200 kg leave: 76% removal, still short. Refinement 2: 3,000 × 0.30 = 900 kg leave: 82% removal, which meets the goal (Diagram 1).
After each example, ask: "Which number is the evidence? Which criterion does it test? Where did part of the impact go?" Stress that a solution can pass one criterion and fail another, and that a refinement is only finished when new data show the missed criterion is met.
Guided Practice15 minutes
Pairs evaluate three invented proposals to cut nitrate from farm fields that drains into a river. The watershed group needs to remove at least 20,000 kg of nitrogen a year (criterion) and can spend at most $50,000 a year (constraint).
Guided practice data: nitrogen reduction proposals (invented)
Proposal
Nitrogen removed (kg/yr)
Yearly cost ($)
Farmland used (ha)
Tree buffer strips along the river
12,000
30,000
40
Precision fertilizer application
9,000
18,000
0
Constructed wetland at the outlet
15,000
60,000
25
Compute the cost per kilogram of nitrogen removed for each proposal ($2.50, $2.00 and $4.00).
Check each proposal alone against the criterion and the constraint. None removes 20,000 kg on its own, and the wetland is also over budget.
Test the three pairs. Only buffer strips plus precision fertilizer meet both: 21,000 kg for $48,000.
Critique the calculation: adding 12,000 and 9,000 assumes the two remove different nitrogen. If some of it would be caught by both, the real total is lower. What monitoring data would settle this?
Name one benefit to natural systems that the table leaves out (the buffer strips add habitat and plant biomass along the river).
Independent Practice10-15 minutes
Each student evaluates a refinement of a school recycling program (invented data). Before the change, the bins collected 420 kg a month, but 30% was contaminated with food and trash, so the hauler rejected it. After clearer labels and lids with shaped slots, contamination fell to 10% while the collected mass stayed at 420 kg.
Students compute the mass actually recycled before (294 kg) and after (378 kg), state whether the refinement worked, and propose one further refinement with the data they would collect to test it. Ask them to say which part of "reduce, reuse, recycle" the program addresses and which part it does not.
Closure5 minutes
Exit ticket: "A factory filter cuts particulate emissions from 60 t to 9 t a year. What is the percent reduction? Name one more piece of data you would need before calling it a good solution." (85%; for example cost, energy use, or what happens to the captured dust.) Return to the warm-up columns and have students label them criteria and constraints.
Differentiation Strategies
For Struggling Students
Give a criteria checklist with a "met / not met" column and a formula card for percent reduction and cost per unit
Start with whole-number data sets and one criterion before adding a constraint
Provide the sentence frame: "The solution meets ___ because the data show ___, but it does not meet ___ because ___. A refinement would be ___."
For Advanced Students
Ask students to test how sensitive a decision matrix is to the weights they chose, and to argue for one weighting
Have students find the break-even point where a costlier solution becomes worth it (for example, the removal rate at which the wetland beats the buffer on cost per kilogram)
Ask students to write the monitoring plan for a geoengineering field test: what to measure, where, and what result would stop the test
Assessment Guidance
What to Look For
Check that students compute percent reduction from the starting amount, not from the final amount, and that they compare results with a stated criterion instead of calling any reduction "good". Look for evaluations that name a trade-off and where the impact moved. Listen for refinements that change one variable and name the new data needed, rather than "make it bigger" or "use better materials". For geoengineering, look for students who separate what a model result shows from whether the approach is acceptable.
02
Classroom Activities
3 Activities
1
Stormwater Filter: Test, Evaluate, Refine
35 minGroups of 3-4
Groups build a filter for parking-lot runoff in an inverted half bottle, pour 500 mL of muddy water through it and measure the flow rate and the clarity of the water that comes out. They evaluate the design against three criteria, then refine one layer and test again.
Criteria, Constraints and Materials
Clarity: the filtered water must read at least 30 cm in the transparency tube (the muddy water reads 10 cm), which is 3 times clearer.
Flow: at least 100 mL per minute, so the filter does not overflow in a storm.
Budget: at most 10 points. Costs: gravel 1 point per cup, coarse sand 1 per cup, fine sand 2 per cup, cotton layer 1, activated carbon 4 per half cup, coffee filter 1.
Procedure and Safety
Wear goggles and gloves. The teacher premixes the muddy water from wet clay slip and fine sand, so there is no dry clay dust, and cuts the bottles beforehand and tapes the cut edges.
Use only the premixed water. Never use real stormwater or ditch water, which can carry bacteria and oil, and never taste any water.
Pour the filtered water into the waste bucket, not the sink (clay clogs drains). Wipe spills at once, since wet floors are slippery, and wash hands at the end.
Time the first 250 mL that comes through, then fill the transparency tube and lower the water level until the disk just shows. Record that height.
Sample Data (invented)
Design A (2 cups gravel, 1 cup coarse sand, coffee filter; 4 points): clarity 18 cm, flow 240 mL/min. Design B (Design A plus 1 cup fine sand; 6 points): clarity 34 cm, flow 120 mL/min. Design C (Design B plus a cotton layer and ½ cup activated carbon; 11 points): clarity 46 cm, flow 90 mL/min.
Discussion Questions
Only Design B meets all three criteria. Show the evidence for each criterion.
Design C gives the clearest water. Which two criteria does it miss, and what does that tell you about "best" solutions?
Propose one refinement to Design B that could raise clarity without dropping flow below 100 mL/min, and describe the test that would show it worked.
What does the transparency tube not measure that a real storm drain would carry?
Modification for Distance Learning
Students analyze the sample data above and a second invented data set posted by the teacher, then submit an evaluation table and one refinement with a prediction.
2
Waste Diversion Decision Matrix
20 minPairs
An invented town sends 12,000 t of trash a year to its landfill and wants to reduce it. Pairs evaluate three local efforts with a weighted decision matrix and test whether the ranking holds when the weights change.
Option Data (invented)
A. Curbside food-scrap composting: diverts 2,400 t a year for $360,000 a year; 72% of surveyed residents support it.
B. Pay-as-you-throw trash bags: reduces trash by 1,800 t a year for $90,000 a year; 41% support.
C. Reusable take-out containers at restaurants: avoids 300 t a year for $60,000 a year; 80% support.
Scoring
Scores from 1 to 5: tonnes diverted A 5, B 4, C 1; cost per tonne A 3, B 5, C 2; public support A 4, B 2, C 5. Weights: tonnes 3, cost 2, support 1. Pairs compute the cost per tonne for each option ($150, $50 and $200) and the weighted totals (A 25, B 24, C 12).
Discussion Questions
Option B has the lowest cost per tonne but does not rank first. Why?
Options A and B together divert 4,200 t, which is 35% of the town's trash. Is that a reduction, a reuse or a recycling effort, and does the difference matter for natural systems?
Change the weights to tonnes 1, cost 2, support 3. Does A still rank first? (It does, with 23 points, while B and C tie at 20.)
Challenge Variation
Pairs add a fourth criterion, such as the greenhouse gas avoided by keeping food scraps out of the landfill, choose its weight and argue whether it changes the recommendation.
3
Geoengineering Review Panel
25 minGroups of 3-4
Groups act as a review panel. Each group reads three invented model-result summaries for large-scale proposals that change the atmosphere or ocean, scores each on five criteria and writes a short evaluation with one refinement, such as a limit or a monitoring rule.
Model-Result Cards (invented)
Card 1, direct air capture: one plant removes 1 million tonnes (1 Mt) of CO2 a year at $400 per tonne and stores it underground; it needs a large supply of low-carbon energy. For scale, human CO2 emissions are about 37 billion tonnes (37 Gt) a year.
Card 2, marine cloud brightening: spraying fine sea-salt particles from ships brightens low clouds; the model cools one ocean region by 0.5 °C, shifts rainfall downwind, and the effect ends within days if spraying stops.
Card 3, ocean alkalinity enhancement: adding finely ground minerals to coastal seawater raises local pH and lets the water take up more CO2; mining, grinding and shipping use energy, and some minerals release trace metals.
Panel Tasks
Score each card from 1 to 5 on: size of the effect, side effects on natural systems, reversibility, cost, and how easily results can be monitored.
For Card 1, compute how many plants would be needed to remove 1% of yearly emissions (370 plants) and the yearly cost ($148 billion).
Write a two-sentence evaluation for each card and one refinement that addresses its weakest criterion.
Discussion Questions
Which cards remove CO2, the cause of the warming, and which only change temperature?
Why do scientists rely on model results for these proposals instead of field data?
What would you want to measure in a small field test before any large-scale use?
Modification for Distance Learning
Each student takes one card, posts a scored evaluation to the class board and replies to two classmates who reviewed the other cards.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Refining a Stormwater Pond (Sediment Leaving per Year)
Invented data for the fifth worked example, drawn to scale. Each refinement changes one design variable. Only the version with both a forebay and a baffle falls below the 1,000 kg line that marks 80% removal of the 5,000 kg entering each year.
Diagram 2: The Evaluate-and-Refine Cycle
The cycle students follow in every activity: set criteria and constraints, collect before-and-after data on the impact, compare the data with each criterion, then change one design variable and test again. A solution can leave the cycle when every criterion is met or when a trade-off is openly accepted.
04
Homework Assignment
~30 min
HS-ESS3-4 Homework: Evaluating and Refining Solutions with Data
Directions: All data sets and model summaries are invented for practice. Show each calculation with units. For every problem, state which criterion each number tests, and end with a one- or two-sentence evaluation or refinement backed by the data.
Part 1: Evaluating with Impact Data (Problems 1-3)
A cement plant releases 2,400 t of nitrogen oxides (NOx) a year. A selective catalytic reduction system lowers this to 480 t a year and costs $3.2 million a year to run. The criteria are at least 75% removal and at most $2,000 per tonne removed. (a) Find the percent removal. (b) Find the cost per tonne removed. (c) Does the system meet both criteria? (d) The system injects ammonia, and a little escapes unreacted. Explain why this is a trade-off to measure.
A highway project filled 12 ha of natural wetland. The builder created an 18 ha replacement wetland nearby. Five years later, surveys find 21 bird species in the replacement and 35 in a natural reference wetland. The agency requires at least 1.5 ha built per hectare lost and at least 75% of the reference bird species. (a) Compute the area ratio and the percent of reference species. (b) Which requirement is met and which is not? (c) Propose a refinement and the data you would collect to test it.
A school of 900 students installs 4 water-bottle refill stations at $1,200 each. Before, 40% of students bought one plastic bottle (10 g) each school day; after, 15% do. The year has 180 school days. (a) How many bottles are avoided in a year? (b) What mass of plastic is that? (c) What is the cost per kilogram of plastic avoided in the first year? (d) Name one measurement that would check the survey numbers.
Part 2: Refining Solutions (Problems 4-5)
A dam has a fish ladder. Each year 2,000 salmon arrive. Only 50% find the ladder entrance, and 70% of those make it to the top. The goal is that at least 60% of arriving fish pass. Refinement X adds an attraction flow that raises the entrance rate to 80%. Refinement Y lowers the step heights and raises the success rate inside the ladder to 85%. (a) How many fish pass now? (b) Find the percent and number of fish that pass with X alone, with Y alone and with both. (c) Which option meets the goal?
A 1,000 m² green roof keeps 50% of the rain that falls on it. In a 20 mm storm (1 mm of rain on 1 m² is 1 L), the storm drain can accept at most 6,000 L of runoff from the roof. (a) How many liters of rain fall on the roof? (b) How much runs off? (c) Refine the design: what is the smallest cistern that would bring the runoff down to the limit? (d) Name one constraint the cistern adds.
Part 3: Large-Scale Solutions (Problem 6)
An invented model summary for ocean iron fertilization: adding iron to a nutrient-poor ocean region makes phytoplankton take up 20 Mt of carbon in a year. Only 25% of that carbon sinks to the deep ocean and stays for more than 100 years; the rest returns to the atmosphere within a few years. The model also shows fewer nutrients reaching waters downstream, which reduces the food available to fish there. Human fossil emissions are about 10 Gt (10,000 Mt) of carbon a year. (a) How much carbon is stored long term? (b) What percent of yearly fossil emissions is that? (c) Convert the stored carbon to CO2 using 44/12. (d) Write an evaluation that uses at least two criteria and the model evidence.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Calculations from Data
Percent reduction, cost per unit and totals are correct with units
Correct method with one calculation or unit error
Criteria and Constraints
Each result is compared with the stated criterion or constraint, and the verdict is explicit
Results computed but not clearly compared with the criteria
Trade-offs
Names where part of the impact moves and how it could be measured
Names a trade-off without saying how to measure it
Evaluation or Refinement
Refinement changes a specific design variable and names the data that would show it works
Refinement is vague ("make it better") or has no test
05
Quiz: 20 Questions
Interactive, with answers
Instructions
All data sets and model summaries are invented for practice. Your score updates as you answer, and Reset quiz clears everything so you or your students can try again.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
A town is choosing a design to clean runoff from a new shopping center before it reaches a creek. Which statement is a criterion rather than a constraint?
Answer: B
A criterion is a measurable goal the solution must achieve, and capturing 90% of the oil and grease is the goal that protects the creek. Choices A, C and D are limits on money, space and time, so they are constraints.
Question 2 of 20 · Multiple Choice
An old coal mine drains water carrying 250 kg of dissolved iron a month into a stream. After a limestone treatment channel is built, the stream receives 45 kg a month. What is the percent reduction?
Answer: C
The reduction is 250 - 45 = 205 kg, and 205 ÷ 250 = 0.82, or 82%. Choice A is the percent that remains (45 ÷ 250). Choice B divides 250 by 45 and misreads the ratio as a percent. Choice D writes the 205 kg reduction as a percent.
Question 3 of 20 · Multiple Choice
Scrubber P removes 900 t of a pollutant a year for $1.8 million. Scrubber Q removes 1,200 t a year for $3.0 million. Which has the lower cost per tonne removed, and by how much?
Answer: A
P costs $1,800,000 ÷ 900 = $2,000 per tonne and Q costs $3,000,000 ÷ 1,200 = $2,500 per tonne, so P is $500 per tonne cheaper. Choice B assumes the bigger system is cheaper per unit. Choice C compares total costs, not cost per tonne. Q still removes more in total, which a panel might value, but that is a different criterion.
Question 4 of 20 · Multiple Choice
A wind farm cuts a region's CO2 emissions, but monitoring data show bird and bat collisions with the turbines. How should an evaluation treat the collision data?
Answer: D
An impact that a solution creates is a trade-off to be measured and weighed, and refinements can reduce it. Choice A drops evidence. Choice B treats a single trade-off as automatic failure. Choice C throws away the local data that best describe this site.
Question 5 of 20 · Multiple Choice
Satellite images show that forest cover in a watershed fell from 800 km² to 680 km² over ten years as farms expanded. What percent of the forest was lost?
Answer: B
The loss is 800 - 680 = 120 km², and 120 ÷ 800 = 15%. Choice C divides by the final area (680) instead of the starting area. Choice D is the percent that remains. Choice A divides the loss by 1,000 instead of the starting area.
Question 6 of 20 · Multiple Choice
An artificial reef was built to restore fish habitat. After three years, divers count 28 fish species on it, compared with 40 on a natural reef nearby. The goal is 75% of the natural reef's species. Which conclusion do the data support?
Answer: C
28 ÷ 40 = 70%, which is below the 75% goal. The reef is not yet meeting it, and three years is a short time for colonization, so continued surveys and a tested refinement are reasonable. Choice A uses a 50% benchmark that is not the goal. Choice B overreaches from one survey. Choice D ignores that a nearby reference reef is exactly the comparison the goal calls for.
Question 7 of 20 · Multiple Choice
Wastewater passes through two treatment stages in a row. Each stage removes 50% of the phosphorus that reaches it. What percent of the original phosphorus do the two stages remove together?
Answer: A
The first stage leaves 50%, and the second removes half of that, leaving 25% of the original. Together they remove 100% - 25% = 75%. Choice B adds the two percents, which counts removal of phosphorus that is already gone. Choice D is the amount remaining, not removed.
Question 8 of 20 · Multiple Choice
In a model study, stratospheric aerosols lower global temperature, but atmospheric CO2 keeps rising as before. Which impact on natural systems would this approach NOT reduce?
Answer: D
Ocean acidification comes from CO2 dissolving in seawater, not from temperature, so reflecting sunlight does nothing to slow it. Choices A, B and C are temperature impacts that cooling could reduce. This is why evaluations separate approaches that remove CO2 from approaches that only reduce warming.
Question 9 of 20 · Multiple Choice
A direct air capture plant removes 0.5 Mt of CO2 a year. Human CO2 emissions are about 37 Gt (37,000 Mt) a year. How many such plants would it take to remove 2% of yearly emissions?
Answer: B
2% of 37,000 Mt is 740 Mt, and 740 ÷ 0.5 = 1,480 plants. Choice A is the 740 Mt target, not the number of plants. Choices C and D are off by a factor of 10 from a place-value slip when converting gigatonnes to megatonnes.
Question 10 of 20 · Multiple Choice
A school waste audit finds 60 kg of trash a week: 24 kg food scraps, 15 kg paper, 9 kg plastic and 12 kg other. If a composting program keeps all the food scraps out of the trash, what percent of the weekly trash does it divert?
Answer: C
24 ÷ 60 = 0.40, or 40%. Choice A reads the 24 kg as a percent. Choice D is the percent that is left in the trash. Choice B is the paper share (15 ÷ 60), not the food scraps.
Question 11 of 20 · Multiple Choice
A company advertises that its new smokestack filter "removes 99% of pollution." Which additional data would you need most to evaluate the claim?
Answer: A
A percent reduction means little until you know which pollutants it refers to and whether it was measured under real operating conditions. Choice B is sales, not evidence about impacts. Choice C is irrelevant. Choice D is a claim, not data.
Question 12 of 20 · Multiple Choice
A 2,000 m² parking lot is repaved with permeable pavement that lets 80% of rainfall soak into the ground. In a 25 mm storm (1 mm on 1 m² is 1 L), how much water runs off?
Answer: D
The rain on the lot is 2,000 × 25 = 50,000 L. If 80% soaks in, 20% runs off: 0.20 × 50,000 = 10,000 L. Choice A is the water that soaks in. Choice B is all the rain, as if the pavement did nothing. Choice C is the rain from only 1 mm (2,000 × 1 = 2,000 L), with nothing soaking in.
Question 13 of 20 · Multiple Choice
Shrimp trawlers test a turtle excluder device, a grate that lets sea turtles escape the net. Over one season, turtles caught drop from 300 to 45, and the shrimp catch drops by 5%. Which evaluation do the data support?
Answer: B
(300 - 45) ÷ 300 = 85% fewer turtles caught, with a 5% loss of shrimp. That is a strong result with a small trade-off, and a refinement (for example, grate spacing) could be tested against the catch loss. Choice D confuses the number still caught with the number saved. Choice C is possible, but it is a claim that would need its own data, such as turtle counts in the area. Choice A turns a trade-off into automatic failure.
Question 14 of 20 · Multiple Choice
After a wastewater plant upgrade, the fish biomass in the stream below it rises from 12 kg to 18 kg per 100 m of stream. What is the percent increase?
Answer: C
The increase is 18 - 12 = 6 kg, and 6 ÷ 12 = 50%. Choice B divides by the new value (18). Choice D is the new biomass as a percent of the old (18 ÷ 12). Choice A reads the 6 kg change as a percent.
Question 15 of 20 · Short Answer
A dust-control system at a gravel quarry cuts particulate emissions from 40 t to 10 t a year, but it sprays 30 million liters of water a year in a region with droughts. The water constraint is at most 20 million liters a year. Evaluate the system and propose one refinement with the data you would collect.
The system gives a 75% reduction ((40 - 10) ÷ 40), so it works on dust, but it fails the water constraint by 10 million liters (30 compared with 20). A refinement might be to spray only on dry, windy days, add windbreak fences, or cover stockpiles, then measure the water used and the dust emitted to check that both limits are met.
Question 16 of 20 · Short Answer
A landfill releases 5,000 t of methane a year. A gas collection system captures 60% of it, and the captured methane is burned to make electricity. The county wants at least 75% captured. (a) How much methane is captured, and how much escapes? (b) How many more tonnes must be captured to meet the goal?
(a) 3,000 t captured (0.60 × 5,000) and 2,000 t escape. (b) The goal is 0.75 × 5,000 = 3,750 t, so 750 t more must be captured, for example by adding collection wells or covering finished cells sooner. Burning the methane releases CO2, which is a trade-off, but methane traps far more heat per tonne, so capturing it is still a large benefit.
Question 17 of 20 · Short Answer
A 250 ha farm loses 1,500 t of soil a year to erosion. Planting strips of native prairie on 25 ha of the fields cuts the soil loss to 150 t a year. (a) What percent of the farmland was converted? (b) What is the percent reduction in soil loss? (c) Evaluate the trade-off in one or two sentences.
(a) 25 ÷ 250 = 10% of the farmland. (b) (1,500 - 150) ÷ 1,500 = 90% less soil loss. (c) Giving up 10% of the cropland cuts erosion by 90% and adds habitat and plant biomass, so the benefit is large compared with the land cost. The farmer would still want data on the crop income lost from the 25 ha.
Question 18 of 20 · Short Answer
A student proposes cleaning up floating ocean plastic with long floating barriers that funnel debris into collection nets. Name two criteria you would use to evaluate the proposal and one unintended impact on natural systems you would test for.
Possible criteria: the mass of plastic removed per year compared with the amount entering that region, and the cost or fuel used per tonne removed. An unintended impact to test: bycatch of the small animals that live at the ocean surface, such as jellies, snails and young fish, measured by sampling what the nets collect. A stronger evaluation also notes that stopping plastic before it reaches the ocean may reduce the impact more.
Question 19 of 20 · Short Answer
A solar farm is built on 200 ha of grazing land. Before construction, a survey found 12 native pollinator species. After native wildflowers are planted under and between the panels, the same survey finds 15. (a) What is the percent change in pollinator species? (b) Evaluate the solar farm's impact on natural systems using the data, and name one more measurement you would want.
(a) (15 - 12) ÷ 12 = 25% more species. (b) On this measure, the planting turned a land-use change into a gain for pollinator diversity, and the farm also displaces fossil electricity. A fuller evaluation would add data such as soil erosion under the panels, the abundance (not just the number of species) of pollinators, or the wildlife that used the grazing land before.
Question 20 of 20 · Short Answer
A panel scores two designs from 1 to 5 on pollutant removal, cost and habitat. Design X scores 4, 2 and 5. Design Y scores 3, 4 and 3. (a) With weights removal 3, cost 2, habitat 1, which design wins? (b) With weights removal 2, cost 3, habitat 1? (c) What does this tell you about a decision matrix?
(a) X: 3(4) + 2(2) + 1(5) = 21; Y: 3(3) + 2(4) + 1(3) = 20. X wins, 21 to 20. (b) X: 2(4) + 3(2) + 5 = 19; Y: 2(3) + 3(4) + 3 = 21. Y wins, 21 to 19. (c) When totals are close, the result depends on the weights, so the panel must justify its weights with the goals of the project and report that the choice is sensitive to them.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does HS-ESS3-4 mean?
HS-ESS3-4 asks students to evaluate or refine a technological solution that reduces the impact of human activities on natural systems. In practice, students compare data on an impact (pollutants released, land disturbed, species lost) before and after a solution, judge it against criteria and constraints, and propose an improvement. The code means High School, Earth and Space Science, core idea 3 (Earth and Human Activity), performance expectation 4.
Is HS-ESS3-4 taught in Earth science or environmental science?
It is usually taught in Earth and Space Science, and it fits naturally in Environmental Science or an integrated science course. Because it is an engineering-style task, it also pairs well with an engineering design unit.
What is the difference between evaluating and refining a solution?
Evaluating means judging an existing solution with data; refining means changing it to fix a weakness the data reveal. The standard accepts either. A complete refinement names the criterion that was missed, changes one design variable and shows with new data that the change works, as in the stormwater pond example on this page.
What counts as a technological solution for HS-ESS3-4?
Any designed device, process or system that reduces an impact counts, from a filter or a scrubber to a recycling program. The Clarification Statement gives a wide range: local efforts such as reducing, reusing and recycling resources, up to large-scale geoengineering that changes the atmosphere or ocean. Choose examples students can evaluate with data.
What data do students use to evaluate a solution?
They use measurements of the impact, such as tonnes of a pollutant released, species counts, biomass, or the area of land disturbed, taken before and after the solution. From these they compute percent reductions and cost per unit of benefit, and they look for new impacts the solution creates. The Clarification Statement names these same kinds of data.
Is geoengineering part of HS-ESS3-4?
Yes, as an example of a large-scale solution, but students evaluate it with model results rather than field data. No large-scale deployment of these approaches has taken place, so the evidence comes from computer models and small experiments. The goal is to judge what the results show against criteria such as side effects and reversibility, not to promote or reject a plan.
What mistakes do students make with HS-ESS3-4?
Frequent mistakes are computing percent reduction from the final value, calling any reduction a success without a criterion, and ignoring impacts a solution moves elsewhere. Another is "refining" with vague changes such as "make it stronger" that cannot be tested. The rubric on this page rewards comparisons with criteria and testable refinements.
How does HS-ESS3-4 connect to the engineering design standards?
It applies the same process as the HS-ETS1 standards to a specific goal: protecting natural systems. HS-ETS1-3 asks students to evaluate solutions with prioritized criteria and trade-offs, and HS-ETS1-4 adds computer simulations of a solution's impact. HS-ESS3-4 supplies the Earth science context and the impact data.
What is a safe hands-on lab for HS-ESS3-4?
A stormwater filter lab works well and uses only classroom-safe materials: gravel, sand, cotton and aquarium carbon in cut plastic bottles, with muddy water the teacher mixes from wet clay slip. Students wear goggles and gloves, never use real stormwater, never taste the water, and pour waste into a bucket instead of the sink. The teacher cuts and tapes the bottles beforehand.
How is HS-ESS3-4 assessed?
It is assessed with tasks that give students data or a model summary and ask for a judgment backed by numbers. Typical items ask for a percent reduction or cost per unit, a comparison with criteria, an identified trade-off, or a refinement with a way to test it. NGSS-aligned tests usually present these tasks as scenarios with data.
07
Related Standards
6 standards
These standards connect to HS-ESS3-4: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
MS-ESS3-3Prerequisite
Design a method for monitoring and minimizing a human impact on the environment
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