MS-LS2-5: Evaluating Design Solutions for Biodiversity and Ecosystem Services
In plain English: MS-LS2-5 is the NGSS middle school performance expectation that asks students to evaluate competing design solutions for maintaining biodiversity and ecosystem services, such as clean water, nutrient recycling and soil that stays in place. Students compare plans with data, criteria and constraints. It is usually taught in grade 6, 7 or 8 life science.
Evaluate competing design solutions for maintaining biodiversity and ecosystem services.
Clarification Statement: Examples of ecosystem services could include water purification, nutrient recycling, and prevention of soil erosion. Examples of design solution constraints could include scientific, economic, and social considerations.
Next Generation Science Standards · Disciplinary Core Idea: Ecosystems: Interactions, Energy, and Dynamics · Official standard
Students evaluate competing design solutions, different plans for the same problem, by asking how well each one maintains biodiversity (the variety of species in a place) and ecosystem services (benefits people get from ecosystems, such as clean water). They read invented test data, compute percents and costs, score solutions in a decision matrix with weights, and argue for a choice while naming its trade-offs. The cases include mangroves that clean shrimp-pond water, park leaves that return nutrients to the soil, and a hillside trail that is losing soil. All data sets on this page are invented for teaching.
The NGSS Clarification Statement says: "Examples of ecosystem services could include water purification, nutrient recycling, and prevention of soil erosion. Examples of design solution constraints could include scientific, economic, and social considerations." MS-LS2-5 has no official Assessment Boundary. Students do the practice of engaging in argument from evidence: they evaluate solutions against criteria and constraints, and they judge whether the evidence is strong enough.
Learning Objectives
By the end of this lesson, students will be able to:
Define biodiversity and ecosystem services, and give examples of water purification, nutrient recycling and prevention of soil erosion
Use data to compare how well competing design solutions maintain an ecosystem service and biodiversity
Sort the constraints on a design into scientific, economic and social, and use them to rule out or rank solutions
Build a weighted decision matrix and write an evaluation that names the trade-offs and the limits of the evidence
Prior Knowledge Required
Students should already be comfortable with:
Matter moves among plants, animals, decomposers and the environment 5-LS2-1
Communities use science ideas to protect resources and the environment 5-ESS3-1
Criteria and constraints of a design problem MS-ETS1-1
Show two photos side by side: a creek running between steep, bare dirt banks, and the same kind of creek with willows and grasses along its banks. Tell students that both creeks carry water to the same town.
Warm-Up Prompt
"List everything the plants along the second creek might be doing for the creek, for the animals that live there and for the people downstream. Which of these would a town have to pay for if the plants were gone?"
Collect answers on the board in two columns that you do not name yet: one for living things (birds, fish, insects) and one for jobs the plants do (holding the bank, shading the water, trapping mud). Later in the lesson, label the columns "biodiversity" and "ecosystem services".
Direct Instruction15-20 minutes
Key words.Biodiversity is the variety of living things in a place. On this page it is measured by counting species (kinds of organisms), for example 15 fish species. Ecosystem services are benefits that people get from working ecosystems, often for free. This lesson uses three from the standard: water purification (cleaning water, for example when roots and mud trap dirt and extra nutrients), nutrient recycling (returning nutrients such as nitrogen from dead leaves and wastes to the soil, where decomposers, the fungi, bacteria and small animals that break down dead matter, release them for plants), and prevention of soil erosion (keeping soil from washing or blowing away). A design solution is a plan or device that people build to solve a problem; competing solutions are different ways to solve the same problem.
How to evaluate.Criteria are what a solution must do to succeed. Constraints are limits it must work within. The Clarification Statement names three kinds: scientific (what works in nature, such as whether a plant survives salty mud), economic (money: building and running costs) and social (what people need or will accept, such as keeping a trail open). A trade-off is giving up some of one thing to get more of another. A decision matrix is a table that scores every solution on every criterion; a weight is a number that makes an important criterion count more. All data sets on this page are invented for teaching.
Water purification: mangrove strip or concrete tank
Invented data. A coastal village raises shrimp in ponds. Water drained from the ponds carries extra nitrogen (a nutrient that makes algae grow fast) into the bay, at 20 mg per liter. Design A sends the drain water through a 3-hectare strip of replanted mangrove trees, which grow in salty mud at the shore. Design B sends it through a concrete settling tank with a pump. After A the water has 8 mg/L of nitrogen; after B it has 6 mg/L. A net survey finds 15 fish species in the mangrove strip and 4 on the bare mud by the tank. Over 10 years, A costs $40,000 and B costs $90,000.
Result: A removes (20 - 8) ÷ 20 = 60% of the nitrogen; B removes (20 - 6) ÷ 20 = 70%. B cleans 10 percentage points better, but A keeps 11 more fish species and costs $50,000 less. If the village criterion is "remove at least half the nitrogen", both designs pass, and A does better on biodiversity and cost.
Nutrient recycling: what to do with a park's fallen leaves
Invented data. A city park collects about 10,000 kg of dry leaves each fall, and about 1% of their mass is nitrogen. Plan 1: rake, bag and truck the leaves to a landfill ($3,000). Plan 2: shred the leaves with mowers and leave them on the lawns ($800). Plan 3: pile them in a compost corner and spread the compost on flower beds in spring ($1,500); about one fifth of the nitrogen is lost while the pile breaks down. Soil samples later hold 4 kinds of small animals under bagged lawns, 9 under mulched lawns and 11 in the composted beds.
Result: Nitrogen in the leaves: 10,000 × 0.01 = 100 kg. Plan 1 returns 0 kg to the park soil, Plan 2 about 100 kg, Plan 3 about 100 × 4/5 = 80 kg. Cost for each kilogram returned: Plan 2 $800 ÷ 100 = $8, Plan 3 $1,500 ÷ 80 = $18.75. Plans 2 and 3 keep nutrients cycling and support more soil animals; Plan 1 sends both to the landfill.
Prevention of soil erosion: fixing a hillside trail (Diagram 1)
Invented data. Rain washes about 6.0 tonnes of soil a year off one 100 m section of a steep park trail. Design A builds wooden steps with gravel ($12,000). Design B moves the trail into gentle switchbacks (a zigzag path, 120 m longer) and plants native shrubs and grasses through jute netting, a mesh that rots away as the roots grow ($7,000). Soil lost per year: A 1.5 t; B 2.4 t in year 1 and 0.9 t in year 2. Plant species within 5 m of the trail: no change 5, A 6, B 14.
Result: A cuts soil loss by (6.0 - 1.5) ÷ 6.0 = 75% at once. B cuts it by 60% in year 1 and (6.0 - 0.9) ÷ 6.0 = 85% in year 2, once the roots hold the soil. Trade-off: A works faster and keeps the trail short; B works better in the long run, costs $5,000 less and nearly triples the number of plant species.
Scientific, economic and social constraints in one decision matrix (Diagram 2)
The park board scores each trail design from 1 (poor) to 3 (good) on four criteria agreed before scoring: soil kept on the slope (scientific, weight 2), plant species (biodiversity, weight 2), cost (economic, weight 1), and hikers' wish for a short route (social, weight 1). Scores: A 2, 1, 1, 3; B 3, 3, 2, 2; no change C 1, 1, 3, 1.
Result: A: 2×2 + 1×2 + 1×1 + 3×1 = 10. B: 3×2 + 3×2 + 2×1 + 2×1 = 16. C: 1×2 + 1×2 + 3×1 + 1×1 = 8. B ranks first. Even if hikers asked to triple the social weight, B would still lead, 20 to 16 for A. A ranking this robust (it does not flip when one weight changes) gives the board more confidence.
After each example, ask three questions: "Which ecosystem service does this solution keep working? What happens to biodiversity? Which constraint, scientific, economic or social, makes the choice hard?" Point out in Example 3 that a fair evaluation looks at more than one year: B looked worse than A in year 1. Diagrams 1 and 2 show Examples 3 and 4.
Guided Practice10-15 minutes
Pairs evaluate three invented plans for a 20-hectare apple orchard. The farmer needs apples to sell, and apple flowers need pollinators (animals such as bees that carry pollen between flowers so fruit forms). Pollination is another ecosystem service.
Guided practice data (invented): three orchard plans, one growing season
Plan
What the farmer does
Wild bee species counted
Apples per tree
Cost per year
P1
Sprays insect killer on a fixed schedule, mows all grass
6
300
$9,000
P2
Plants wildflower strips between rows, sprays only when pests are found
18
320
$7,500
P3
Rents honeybee hives, sprays on a fixed schedule
6
330
$11,000
For each plan, name the ecosystem service it depends on and say whether it helps or harms biodiversity.
Find how many more wild bee species P2 has than P1, and how many more apples per tree P3 gives than P2.
Identify one trade-off between P2 and P3.
Build a decision matrix with three criteria: wild bee species (weight 2), apples per tree (weight 2) and cost (weight 1). Score each plan from 1 to 3, using 3 for the best value in each column, 1 for the worst and the same score for a tie. Add the weighted totals.
Write two sentences: which plan you recommend, and one more piece of data you would want before deciding.
Independent Practice10-15 minutes
Each student writes a one-paragraph evaluation from a new invented case. The town of Elm Ridge gets its drinking water from a reservoir fed by streams that run through 400 hectares of forest. A developer wants to buy the forest and build homes.
Independent practice data (invented): two ways to keep Elm Ridge's water clean
Option
Building cost
Yearly cost
Bird species in the area
A: town buys the forest and keeps it as a preserve; roots and soil keep cleaning the stream water
$6 million
$100,000 in property taxes the town will not collect
48
B: homes are built; town builds a large water filtration plant
$15 million
$400,000 to run the plant
about 20 expected
Students find the total cost of each option over 20 years, name the ecosystem service and the biodiversity at stake, and name one social constraint (for example, families who want new homes in town). Their paragraph ends with a recommendation and one piece of evidence that would change their mind.
Closure5 minutes
Exit ticket: "Name one design solution from today that kept an ecosystem service working and also protected biodiversity. Name one constraint that made it harder to choose." Return to the warm-up board and label the two columns. Ask which creek photo would need a design solution to replace the work its plants did.
Differentiation Strategies
For Struggling Students
Give a blank decision matrix with the criteria, weights and a "score × weight" column already drawn
Provide three colored sticky notes labeled scientific, economic and social for sorting constraints
Offer a sentence frame: "I recommend ___ because it ___. The trade-off is ___. I would also want to know ___."
For Advanced Students
Ask students to change one weight in Example 4 until the ranking flips, and explain what that tells the park board
Have students design a combined solution, such as mangroves plus a small tank, and predict its scores
Ask students to write a monitoring plan: what to count, where, and for how many years, to check a chosen solution
Assessment Guidance
What to Look For
Check that students judge each solution on both biodiversity and at least one ecosystem service, not only on cost or on one number. Look for evaluations that name the constraint type (scientific, economic, social) and a trade-off. Listen for students who treat one short test as proof, or who forget that a solution may improve over time, as the planted hillside did.
02
Classroom Activities
3 Activities
1
Erosion Trays: Bare Soil, Straw or Roots
25 minGroups of 3-4
Groups test three competing designs for keeping soil on a slope, using model hillsides in roasting pans. They measure the soil that washes off, then weigh the result against cost and other criteria.
Procedure
Fill three pans with the same potting soil, 4 cm deep. Pan 1 stays bare. Pan 2 gets a 2 cm layer of straw (mulch). Pan 3 is the pan of grass the teacher sowed 10-14 days earlier.
Prop the uncut end of each pan on two books so all three have the same slope. Set a plastic tub under the notch.
Pour 1 L of water from the watering can over the high end of the pan, evenly, over 30 seconds.
Pour the runoff into a clear jar, let it settle for 10 minutes, then pour off the clear water and measure the settled soil with the measuring jug.
Safety: wipe up spills at once so no one slips, and wash hands after handling soil.
Sample Data (invented)
Settled soil washed off: bare pan 120 mL, straw pan 40 mL, grass pan 15 mL. Cost card: straw costs $2 per pan and must be replaced when it blows away; grass seed costs $1 per pan but needs about two weeks to grow.
Discussion Questions
By what percent did each design cut the soil loss compared with the bare pan?
The grass pan lost the least soil. Which constraint, scientific, economic or social, makes the grass harder to use right after a wildfire or a construction project?
Which design could also add biodiversity to a real hillside, and how would you measure that?
Modification for Distance Learning
Students use three baking trays or shoebox lids at home with an adult's permission, or analyze the sample data and a teacher video of the test.
2
Schoolyard Council: Lawn, Meadow or Garden?
25 minGroups of 5 (one role each)
A school must decide what to do with a 600 m² lawn behind the gym. Each group member takes a role card, reads the invented data card, and the group builds a decision matrix before it votes.
Data Card (invented)
Option 1, keep the mowed lawn: 3 pollinator species seen in 20-minute counts at similar sites; $0 to set up; 40 hours of mowing a year.
Option 2, native wildflower meadow, mowed once a year: 21 pollinator species; $1,800 for seed and soil preparation; 8 hours of work a year.
Option 3, vegetable and flower garden run by a student club: 12 pollinator species; $2,500 for beds, soil and tools; 120 hours of work a year.
Role Cards
Science teacher: wants a place to study pollinators and plants.
Coach: the soccer team practices on the lawn twice a week.
Custodian: mowing time comes out of other jobs.
School nurse: two students have bee sting allergies and carry medicine.
Budget office: this year's limit is $2,000.
Discussion Questions
Which option fails the budget constraint, and by how much?
The meadow has the most pollinator species and the least upkeep. What social constraints might still make the council reject it?
Could a combined design, such as a meadow on half the lawn, meet more criteria? Score it.
Modification for Distance Learning
Assign roles in breakout rooms and build the matrix together in a shared spreadsheet.
3
Leaf Litter Count: Bag It or Leave It?
20 minPairs
Pairs count the kinds of small animals in two soil samples the teacher collected that morning on school grounds: one from under trees where leaves were left, and one from a raked area. The counts become evidence for evaluating the leaf plans in Example 2.
Procedure
Safety: wear gloves, move animals only with a plastic spoon, and do not touch any animal with bare hands. Wash hands at the end. The teacher collects samples away from broken glass and poison ivy.
Spread each 1 L sample on a white tray. For 10 minutes, use hand lenses to sort animals by kind (earthworms, pill bugs, millipedes, beetle larvae, springtails and so on). Record the number of kinds and the number of animals.
Return the samples and animals to where they came from within 30 minutes.
Many of these animals are decomposers. How does that connect biodiversity to nutrient recycling?
Use your counts and the Example 2 data to evaluate the three leaf plans. Which plan would you choose for a park, and which constraint might stop it?
Why is one pair of samples weak evidence? What would make it stronger?
Challenge Variation
Pairs plan a fair test of whether shredded leaves on a lawn raise the number of kinds of soil animals, with repeated samples over several weeks.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Soil Lost From a Trail Section With Each Design (Example 3)
Invented data from Example 3, drawn to scale: tonnes of soil washed off one 100 m trail section in a year. Wooden steps (A) work at once. Plants with switchbacks (B) lose more soil than the steps in year 1 and less in year 2, once roots hold the slope.
Diagram 2: Weighted Decision Matrix for the Trail Designs (Example 4)
Each bar stacks the four weighted scores from Example 4, drawn to scale. Soil kept and plant species have weight 2; cost and the hikers' wish for a short route have weight 1. Design B has the largest total.
04
Homework Assignment
~30 min
MS-LS2-5 Homework: Evaluating Design Solutions
Directions: All data are invented for practice. Show your calculations. In every evaluation, say how the solution affects biodiversity and at least one ecosystem service, name the constraints (scientific, economic or social), and name a trade-off.
Part 1: Ecosystem Services Under Pressure (Problems 1-3)
Lake Hollis supplies a town's drinking water. Rain washes phosphorus (a nutrient that feeds algae) from farm fields into the lake. Invented data. Option A: floating wetlands, rafts of native plants whose roots take up nutrients, cost $60,000; phosphorus in the lake falls from 0.10 mg/L to 0.06 mg/L, and bird species using the lake rise from 22 to 27. Option B: extra filters at the water plant, cost $150,000; tap water is clean, but the lake stays at 0.10 mg/L, algae still bloom, and bird species stay at 22. The town's budget is $100,000. (a) By what percent does Option A lower the phosphorus in the lake? (b) Which ecosystem service does each option maintain or replace? (c) Evaluate both options against the budget and against biodiversity, and recommend one.
Cattle on a ranch walk down a stream bank to drink, and the bank is falling into the water. Invented data for 200 m of bank. Option A: a fence 5 m back from the stream, willow plantings and a water trough for the cows, cost $9,600; soil lost per year drops from 40 t to 8 t within 3 years, and kinds of stream insects rise from 5 to 12. Option B: a wall of large rocks along the bank, cost $34,200; soil lost drops to 2 t right away, and kinds of stream insects rise to 6. (a) Find the percent drop in soil loss for each option. (b) Find each option's cost for each tonne of soil saved per year. (c) Explain why the water trough matters to the rancher, and name its constraint type. (d) Write an evaluation that uses all your numbers.
A school cafeteria throws away 40 kg of fruit and vegetable scraps each week for 36 school weeks. Invented data. Option A: send the scraps to the landfill with the trash, no extra cost. Option B: a city pickup takes the scraps to a compost farm for $15 a week, and the compost goes to city parks. Option C: the science club runs three compost bins in the school garden, $360 once, but the bins can handle only 25 kg a week. (a) How many kilograms of scraps is that in a school year? (b) What does Option B cost for the year? (c) What percent of the weekly scraps can Option C handle? (d) Which options keep nutrients cycling, and what combined design would handle all the scraps?
Part 2: Evaluating and Critiquing Solutions (Problems 4-6)
A highway through a forest cuts animals off from half their habitat, and many are hit by cars. Invented data. Option A: a wildlife bridge over the road with fences ($4,000,000), crashes with animals drop by 85%, 14 species use it. Option B: fences with three small tunnels ($900,000), crashes drop by 60%, 8 species use them. Option C: warning signs ($20,000), crashes drop by 10%, no species gain a safe crossing. Scores from 1 to 3: fewer crashes A 3, B 2, C 1; species helped A 3, B 2, C 1; cost A 1, B 2, C 3. (a) Find each total with weights: crashes 2, species 2, cost 1. (b) The state can spend at most $1,000,000. Which option does this constraint rule out, and which option should the state choose? (c) Explain why constraints should be checked before the scores are compared.
Sand dunes protect a beach town from storm waves, and beach grass and nesting shorebirds live on them. A student report compares two designs for keeping dune sand in place: (A) wooden sand fences and (B) newly planted native beach grass. The report says: "On one windy afternoon, sand blown onto the boardwalk was 1.0 cm deep behind the fences and 1.5 cm deep behind the grass. Fences work best, so the town should build fences." (a) Name three weaknesses in this evaluation. (b) Name one ecosystem service and one way biodiversity could be measured on the dunes. (c) Plan a better evaluation: what would you measure, for how long, and how would you include cost?
A county mows 300 km of roadsides 6 times a year, at $45 per kilometer for each mowing. Invented proposal: mow the full roadside only 2 times a year and mow a 2 m safety strip next to the pavement the other 4 times, at $20 per kilometer, so drivers can still see deer. Butterfly species counted per kilometer: 4 with frequent mowing, 11 with less mowing. Taller plants also have deeper roots that hold ditch banks. (a) Find the yearly cost of each plan. (b) Build a decision matrix with at least one scientific, one economic and one social criterion, and score both plans. (c) Write your recommendation, naming one trade-off and one question you would investigate before deciding.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Using the Data
Correct percents, costs and totals, with units
Most calculations correct, or units missing
Biodiversity and Services
Judges every option on biodiversity and on a named ecosystem service
Discusses only one of the two, or names the service without evidence
Constraints and Trade-offs
Names constraint types correctly and uses them to rule out or rank options
Mentions cost or people, but does not use the constraint in the decision
Evaluation
Clear recommendation backed by numbers, with a trade-off and a limit of the evidence
Recommendation given without evidence, or with no trade-off
05
Quiz: 20 Questions
Interactive, with answers
Instructions
All data sets are invented. Read each case carefully: some questions ask you to calculate, others to evaluate a solution. 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
Which of these is an ecosystem service?
Answer: B
An ecosystem service is a benefit that comes from a working ecosystem: the marsh plants clean the water for free. Choice A is a human-built device, not an ecosystem. Choice D removes leaves, which stops nutrient recycling instead of providing it.
Question 2 of 20 · Multiple Choice
Pond 1 holds 500 fish of 2 species. Pond 2 holds 120 fish of 9 species. Which statement about biodiversity is correct?
Answer: C
Biodiversity is the variety of living things, measured here by the number of species: 9 is more than 2. Choice A counts individual fish, not kinds of fish. Choice D uses size, which says nothing about variety.
Question 3 of 20 · Multiple Choice
A town plans a fence to keep people off a restored wetland. Neighbors say the fence must not block their view of the lake. What kind of constraint is this?
Answer: C
The limit comes from what people want and will accept, so it is social. Choice B would be about money. Choice A would be about how nature works, such as whether wetland plants survive a dry summer.
Question 4 of 20 · Multiple Choice
Invented data: a test wetland lowered the mud in stream water from 40 mg/L to 14 mg/L. By what percent did it lower the mud?
Answer: C
The drop is 40 - 14 = 26 mg/L, and 26 ÷ 40 = 0.65, or 65%. Choice A writes the drop in mg/L as if it were a percent. Choice B is 14 ÷ 40, the share of mud that is left. Choice D divides 40 by 14.
Question 5 of 20 · Multiple Choice
Which farm practice keeps nutrient recycling going in a field after harvest?
Answer: D
Stalks left on the field are broken down by decomposers, which return their nutrients to the soil. Choice A removes the nutrients from the field. Choice C kills the decomposers that do the recycling.
Question 6 of 20 · Multiple Choice
A decision matrix uses weights: cleans water ×3, cost ×1, species kept ×2. Plan X scores 2 for cleaning water, 3 for cost and 1 for species kept. What is its weighted total?
Answer: C
2 × 3 + 3 × 1 + 1 × 2 = 6 + 3 + 2 = 11. Choice A adds the scores without weights (2 + 3 + 1). Choice B pairs the weights with the wrong criteria (2 × 2 + 3 × 1 + 1 × 3). Choice D adds each weight to its score instead of multiplying.
Question 7 of 20 · Multiple Choice
A town can build a seawall that protects homes within a year, but the wall would cover the salt marsh where young fish grow. Which statement names the trade-off?
Answer: A
A trade-off is giving up some of one thing to get more of another: quick protection for homes in exchange for losing marsh habitat and the fish it supports. Choice B ignores the cost to the fish. Choice D is wrong because the homes do gain.
Question 8 of 20 · Multiple Choice
Students want to know whether straw or grass seed better prevents erosion on a slope. Which plan is the fairest test?
Answer: C
A fair test changes only the design and keeps the soil, slope and amount of water the same, and repeating the test makes the result more reliable. Choice A changes the slope too, so any difference could come from the slope. Choice B measures opinion, not soil loss.
Question 9 of 20 · Multiple Choice
Invented data: Option 1 costs $7,200 and keeps 3 tonnes of soil a year from washing away. Option 2 costs $10,000 and keeps 4 tonnes a year. What is Option 1's cost for each tonne kept per year?
Answer: B
$7,200 ÷ 3 = $2,400 for each tonne. Choice A divides Option 1's cost by Option 2's 4 tonnes. Choice C is Option 2's cost per tonne ($10,000 ÷ 4). Choice D multiplies instead of dividing.
Question 10 of 20 · Multiple Choice
Which of these is a social constraint on a plan to restore a lake shore?
Answer: C
Keeping fishing open is about what people need and accept, so it is social. Choice A is economic. Choice B is scientific, a limit set by how plants live. Choice D is a criterion about erosion.
Question 11 of 20 · Multiple Choice
Design A removes the most nitrogen from a stream, but it costs twice the budget. What should an evaluation conclude?
Answer: B
A solution must stay within its constraints. If A cannot be paid for, it cannot be built, however well it scores; the team could look for a cheaper version or more funding. Choices A and C ignore the budget constraint. Choice D treats a real limit as if it did not exist.
Question 12 of 20 · Multiple Choice
Why does planting native grasses on a bare slope prevent soil erosion?
Answer: D
Roots bind soil particles together, and leaves and stems slow raindrops and runoff, so less soil is carried away. Choice B is too strong: plants take up some water, but heavy rain still runs off. Choice C confuses erosion control with rock formation.
Question 13 of 20 · Multiple Choice
Plan M scores 3 for habitat and 1 for cost. Plan N scores 1 for habitat and 3 for cost. With equal weights both total 4. If habitat gets weight 2 and cost stays at weight 1, what happens?
Answer: D
M: 3 × 2 + 1 × 1 = 7. N: 1 × 2 + 3 × 1 = 5. Choice A swaps the two totals. Choice B doubles both of Plan M's and none of Plan N's scores. Choice C forgets to apply the new weight.
Question 14 of 20 · Multiple Choice
A city must choose between a concrete channel and a restored stream with plants on its banks. Both carry the same floodwater. Which data would best show which design maintains more biodiversity?
Answer: A
Biodiversity is the variety of species, so counting kinds of fish and insects in both designs measures it directly. Choice C measures water speed, which is about flooding, not species. Choice B is about people.
Question 15 of 20 · Short Answer
Invented data: a small lake in a town park has algae blooms. Option A plants a 10 m strip of native plants around the shore for $1,200; nitrogen entering the lake falls from 6 mg/L to 3 mg/L, and frog species rise from 2 to 4. Option B installs a pump that bubbles air into the water for $1,900 plus $150 a year for electricity; nitrogen entering stays at 6 mg/L, and frog species stay at 2. The budget is $1,500. Evaluate both options and recommend one.
Option A lowers incoming nitrogen by (6 - 3) ÷ 6 = 50%, doubles the frog species and costs $1,200, within the budget. Option B costs $1,900 before electricity, so it fails the economic constraint, and it does not lower the nitrogen or help frogs. Recommend A. A full answer names the service (water purification) and notes a limit, such as one year of data.
Question 16 of 20 · Short Answer
Invented data: on a test slope, a cover of native plants cut soil loss from 10 tonnes to 4.5 tonnes a year, and a plastic sheet cut it to 0.3 tonnes. Find both percent reductions, then give two reasons the plastic sheet could still be the worse design.
Plants: (10 - 4.5) ÷ 10 = 55%. Plastic: (10 - 0.3) ÷ 10 = 97%. The plastic could still be worse because nothing lives under it (it lowers biodiversity), it stops leaves and roots from returning nutrients to the soil, it tears and breaks into litter, and it must be replaced. The plants keep improving as their roots grow.
Question 17 of 20 · Short Answer
Boat anchors are tearing up seagrass meadows in a bay, where young fish and crabs shelter. A park plans fixed mooring buoys that boats tie to instead of anchoring. Name one scientific, one economic and one social constraint on this plan, and one criterion about biodiversity.
Sample answer. Scientific: the buoy anchors must hold in sand during storms without damaging seagrass. Economic: buoys and their upkeep must fit the park budget. Social: boaters must accept tying up instead of anchoring where they like, and there must be enough buoys. Biodiversity criterion: the number of fish and crab species in the meadow stays the same or rises over two years.
Question 18 of 20 · Short Answer
A classmate says: "The solution that costs the least is always the best one." Use an example from this lesson's homework or quiz to argue against this claim.
Sample answer. In Problem 4 the warning signs cost only $20,000, but they cut crashes by just 10% and gave no species a safe crossing. A cheap solution that does not meet the criteria is not a solution. Cost is one constraint; a good evaluation checks every criterion and constraint, then picks the option that meets them best.
Question 19 of 20 · Short Answer
A decision matrix uses weights: species kept ×3, cleans water ×2, cost ×1. Design 1 scores 2, 3 and 2. Design 2 scores 3, 2 and 2. Find both weighted totals and say which design ranks first.
Design 1: 2 × 3 + 3 × 2 + 2 × 1 = 14. Design 2: 3 × 3 + 2 × 2 + 2 × 1 = 15. Design 2 ranks first. A full answer adds that the ranking is only as good as the scores and weights, so the team should agree on them before scoring.
Question 20 of 20 · Short Answer
Explain how one restored wetland can maintain both biodiversity and an ecosystem service at the same time. Name two kinds of data you would collect to evaluate it.
Wetland plants slow the water, and their roots and the mud trap dirt and take up extra nutrients, which cleans the water (water purification). The same plants give food and shelter to many insects, frogs, fish and birds, which raises biodiversity. Data: nutrient or mud levels in the water flowing in and out, and counts of species before and after the restoration, repeated over several years.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does MS-LS2-5 mean?
MS-LS2-5 asks students to evaluate competing design solutions for keeping biodiversity and ecosystem services working. Students compare two or more plans, such as planting a wetland or building a treatment tank, using data, criteria and constraints. The code means Middle School, Life Science, core idea 2 (Ecosystems: Interactions, Energy, and Dynamics), performance expectation 5.
What grade is MS-LS2-5 taught in?
It is a middle school standard for grades 6-8, and schools place it in grade 6, 7 or 8 life science. It often closes an ecosystems unit, after students have studied food webs, matter cycling and how changes affect populations.
What are ecosystem services, in simple words?
They are the useful jobs that healthy ecosystems do for people. The Clarification Statement names water purification, nutrient recycling and prevention of soil erosion. Pollination of crops, flood control and shade are other examples.
Does MS-LS2-5 have an assessment boundary?
No. MS-LS2-5 has no official Assessment Boundary. The Clarification Statement gives the examples: ecosystem services such as water purification, nutrient recycling and prevention of soil erosion, and design constraints that are scientific, economic and social.
What is the difference between criteria and constraints?
Criteria say what a solution must do to succeed, for example "remove at least half the nitrogen". Constraints are limits it must work within, such as a budget, the plants that can survive in a place, or what neighbors will accept. A solution that misses a constraint is ruled out, however well it meets the criteria.
How do students measure biodiversity in a middle school lesson?
The simplest way is to count species, or kinds of organisms, in the same area and the same amount of time for each design. Students can sort leaf litter animals, count pollinators in 20 minutes, or use survey data. Comparing counts before and after a design is put in place is stronger than a single count.
How does MS-LS2-5 connect to engineering design?
It uses the same evaluation tools as MS-ETS1-2, such as decision matrices, but the criteria must include biodiversity and ecosystem services. Students who have built a decision matrix for a device can use it here for a wetland, a trail or a farm.
What is a decision matrix?
It is a table with the solutions in the rows and the criteria in the columns. Each solution gets a score for each criterion, the scores are multiplied by weights that show how much each criterion matters, and the weighted scores are added. Teams should agree on the scores and weights before they look at the totals.
What mistakes do students make with this standard?
A common one is judging solutions on one number, often cost or one test result. Another is forgetting that living solutions, such as plantings, take time to work, so a short test can be unfair to them. Ask students to name a service, a biodiversity measure, a constraint and a trade-off in every evaluation.
Can MS-LS2-5 be taught without a field trip?
Yes. Erosion trays, data cards and role-play councils cover the standard well indoors. A short schoolyard sample, such as a leaf litter count, adds real data; students wear gloves, move animals only with spoons and return them where they were found.
07
Related Standards
6 standards
These standards connect to MS-LS2-5: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
5-ESS3-1Prerequisite
Combine information on how communities use science to protect resources
Lesson coming soon
5-LS2-1Prerequisite
Model how matter moves among plants, animals, decomposers and environment
Lesson coming soon
Alongside
MS-LS2-4Parallel
Argue from evidence that ecosystem changes affect populations
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