Bats, Pigs and People: Choosing a Plan to Prevent Nipah

Investigation question: Fruit bats near Green Valley's pig farms can carry Nipah virus, but the same bats pollinate fruit trees and spread forest seeds. With $6 million for ten years, which plan or package should the district choose to protect people, the bats and farm families, and does the answer hold up when different people's priorities are weighted and the estimates turn out worse than expected?

Scientific purpose

Students act as an advisory group for an invented farming district in Southeast Asia, each speaking for a stakeholder: a pig farmer, the district health officer, a durian orchard grower and the district budget officer. They read real background on Nipah virus and fruit bats and simulated data on five competing plans and six two-plan packages, negotiate one agreed set of criteria weights with weight chips, turn the data into scores with fixed scoring rules, compute weighted totals, recheck the ranking under every stakeholder's weights and under worst-case estimates, and write a recommendation that separates what the data show from what the group values.

Why this helps students with this chapter

Real environmental decisions rarely have one right answer, and students often swing between 'science decides' and 'it is all opinion'. A weighted matrix puts each in its place: data become scores through rules anyone can check, and values become weights that people argue about openly. This case adds a twist from the lesson's emerging-disease section: the fix that sounds simplest, getting rid of the bats, scores worst once biodiversity and ecosystem services are counted. Rechecking with each stakeholder's weights shows why a pig farmer and a health officer can read the same data and disagree, and the worst-case check shows that the highest score is not always the safest bet.

Standards connections

MS-LS2-5 (assesses, evaluating competing design solutions for maintaining biodiversity and ecosystem services, with scientific, economic and social constraints): Students evaluate five competing solutions and six packages against criteria that include a wild species and the ecosystem services it provides (fruit bats that pollinate durian and spread forest seeds), human health, farm income, cost, fairness and certainty, then defend a choice. This matches the PE as written, including the scientific, economic and social constraints named in its clarification statement.

MS-ETS1-2 (assesses, a systematic, weighted evaluation of competing solutions with sensitivity and worst-case checks): Students apply one systematic process, fixed scoring rules and weighted totals, to every competing plan and package against the same criteria and the $6 million constraint, then test how the ranking holds up under each stakeholder's weights and under worst-case estimates. That is the PE as written: the process is supplied, and students carry it out, check it and judge what the results mean.

Roles (rotate each session)

• Pig farmer and facilitator: Speaks for the district's 60 pig farms, keeps the discussion moving and makes sure every stakeholder speaks before the group agrees on weights.
• District health officer and recorder: Speaks for farmworkers and their families and records the agreed weights, the score matrix and the totals.
• Durian orchard grower and checker: Speaks for the fruit growers whose trees bats help pollinate and checks every score against the scoring rules and every multiplication.
• District budget officer and timekeeper: Speaks for the district's $6 million fund, keeps the group on schedule and confirms that any package stays within budget.

Materials

Estimated cost: 2 to 4 per class (estimate) (an estimate; About 3 printed pages per student (about 90 for a class of 30) plus a two-page case file and a card sheet per group (about 25 more for 8 groups), at roughly 2 to 3 cents a page on a school copier; weight chips are cut from scrap cardstock.)

Safety

• Paper-only activity: the only physical hazards are paper edges and scissors. Use blunt-tip scissors if students cut their own weight chips.
• The case involves a disease that has killed people. Some students may have family experience of serious illness or of farming; keep the discussion about evidence and choices, not about blame, and let students step out of a role if it is uncomfortable.
• Stakeholder roles are perspectives, not judgments of real people or places; the district is invented.

Teacher preparation and setup

1. Print the case file and stakeholder cards for each group and the recording sheet for each student. Cut 20 weight chips per student, or have students cut them in the first minutes.
2. Assign stakeholder roles so every group has all four; in a group of three, the facilitator also speaks for the budget officer.
3. Draw the class results chart: group, agreed weights, top single plan, chosen package, and the winner in the worst-case check.
4. Score plan A yourself with the scoring rules so you can model the step from data to score.
5. Tell the class that Green Valley District and all of its numbers are invented for teaching, while the background facts about Nipah virus and fruit bats are real. The topic is a deadly disease, so keep the focus on prevention and on how communities make choices.

Investigation design

Student procedure

1. Read the background and both data tables aloud as a group, one section per stakeholder. Each stakeholder underlines the numbers their person cares about most.
2. Stakeholder case (5 minutes). Read your card. Lay out your 20 weight chips (5 points each) to match your stakeholder's weights, prepare a 30-second case for your top criterion, and answer q1.
3. Negotiate (10 minutes). Put everyone's chips on the table. The facilitator asks each stakeholder for their 30-second case. Agree on one set of weights that totals 100 and that every member can accept, record it in the weights table and answer q2.
4. Score (8 minutes). Use the scoring rules to turn each single plan's data into a score from 0 to 4 on each criterion and fill the score matrix (q3). The checker confirms every score against the rules.
5. Compute. For each plan, multiply each score by its weight and add the six products. Do it first with the practice weights (q4), then with your agreed weights; split the four stakeholder columns among the group so the totals table is complete (q5, q6).
6. Package. Choose one package from the package table, score it with the same rules and compute its total with the practice weights and with your agreed weights (q7).
7. Worst-case check. Rescore human health for plans A and B and for your package using the top of each likely range, and recompute their practice-weight totals (q8).
8. Recommend. Write the group's recommendation to the district council (q11), post your weights, winners and package on the class chart, and answer the remaining questions on your own.

Expected observations

• Score matrix (central estimates; human health, bats, farm income, cost, fairness, certainty): A 4, 4, 3, 1, 3, 3; B 3, 4, 4, 2, 3, 2; C 2, 0, 1, 4, 1, 1; D 2, 4, 2, 3, 4, 3; E 1, 4, 4, 4, 4, 1.
• Practice-weight totals: A 320, B 310, D 285, E 280, C 155. Packages: B + E 340, B + D 335, A + D 305, A + E 305, D + E 290, C + D 155.
• Stakeholder winners among single plans: pig farmer E (325, with B close at 320), health officer A (330), orchard grower B (345, with A at 340), budget officer E (295). Including packages: pig farmer B + D or B + E (335), health officer B + D (340), orchard grower B + D (365), budget officer still E alone (295).
• Worst case with practice weights: A 320; A + D, A + E and B + D 305; B and B + E 280; D 255; E 250; C 95.
• Plan C ranks last for every stakeholder, including the budget officer, whose weights favor its low cost.

Likely difficulties

• Groups argue about weights before reading the data. Insist on the 30-second cases first, each tied to a number from the case file.
• Scoring fairness: B counts as 'users pay a small cost' (3), A as 'a group loses some income for 3 years or less' (3), C as 'loses income for good with no payment' (1). Have the checker read the 'Who pays or loses' column aloud for each plan.
• Mixing up the central estimate and the likely range. Score with the central number until the worst-case check in step 7.
• Arithmetic load: six products per plan for each weight set. Split the stakeholder columns among the group and have the checker verify one column.
• Treating the top score as the answer. Require the second-place option and the accepted tradeoff in every recommendation.

Structured debrief

1. Post every group's agreed weights and winner. Ask why groups that read the same data chose different plans. The data were identical; the weights were not.
2. Show the stakeholder results: moving the pens (A) wins for the health officer, bat-proof sheds (B) for the orchard grower, and feeding the bats elsewhere (E) for the pig farmer and the budget officer. With the practice weights, the package B + E scores highest of all (340). Ask which option every stakeholder could live with, even if it is nobody's first choice.
3. Run the worst-case check together. Using the top of each range, B falls from 310 to 280 and B + E from 340 to 280, while A holds at 320 because even its worst case stays at 10 percent. Discuss what a district should do when the best-scoring package is also less certain: choose the sure thing and its costs, or choose the package and monitor closely so it can switch plans quickly.
4. Spend a minute on plan C. Removing the bats sounds like removing the problem, yet it scores worst: it barely lowers the risk, may scatter the bats toward other farms, destroys a pollinator and seed spreader, and shifts the cost onto orchard growers. Connect to the lesson's Nipah section: the fixes that worked kept bats and pigs apart rather than destroying the bats.
5. Close on the lesson's final section: science supplied the chances, costs and colony sizes; the weights are a community's values.

Recording sheet: what students fill in

Lab 3 recording sheet: Bats, Pigs and People

Background. Large fruit bats called flying foxes are the natural host of Nipah virus; infected bats usually do not get sick. In Malaysia and Singapore in 1998 and 1999, pigs on farms with fruit trees caught the virus, most likely from bitten fruit and saliva that feeding bats dropped into the pens, and passed it to the people who worked with them. More than 300 people fell ill and more than 100 died, and more than a million pigs were killed to end the outbreak. Since 2001, people in Bangladesh and India have caught it mostly from fruit or raw date palm sap that feeding bats contaminated, and it can also spread from person to person. There is still no approved vaccine or medicine for people. Health agencies advise protecting pig feed and pig sheds from bats and thinking about bats when choosing where to build a pig farm. Fruit bats are valuable too: flying foxes help pollinate durian, one of Southeast Asia's most valuable fruit crops, and carry the seeds of many forest trees. Bat experts warn that chasing a roost away can simply move the bats to other trees, and there is no evidence that killing or chasing bats stops Nipah from spreading.

Green Valley District. The district has 60 pig farms, durian and other fruit orchards, and a forest roost of about 15,000 flying foxes 2 km from the nearest farms. Last year Nipah virus was found in pigs in a neighboring district. The health office estimates that with no action, the chance of a Nipah outbreak in people here within 10 years is about 40 percent. The district has $6 million to spend over 10 years.

Package A + B ($7.0 million) is over budget. Combined chances are the science team's estimates; they are not found by adding or multiplying the single-plan numbers.

Analysis questions: answer key

Individual evidence of learning

Each student submits the stakeholder case (q1), the score matrix (q3), the weights and totals tables, and their own answers to q4 to q12, including the written recommendation (q11). The recommendation, the stakeholder comparison (q6), the worst-case check (q8) and the plan C explanation (q9) are the evidence for evaluating competing solutions for maintaining biodiversity and ecosystem services.

Assessment criteria

Accessibility adaptations

• For students who need support, pre-score plan A in the matrix as a model and provide a multiplication grid for the weighted totals.
• Stakeholder cards can be read aloud in pairs; multilingual learners can prepare their case with the frame 'My stakeholder cares most about ___ because the case file shows ___.'
• Weight chips make the negotiation physical; a student who prefers not to speak can show their weights with chips and a written card.
• Print the data tables in large type, or give students with low vision a digital copy they can zoom.

Low-cost alternative

Project the case file and data tables instead of printing them, and have students record weights and scores in their notebooks; tally marks in rows of five can replace the paper weight chips.

Model limitations

Green Valley District and every number in its data tables are invented for teaching, although the background facts about Nipah virus and fruit bats are real. Real risk estimates would come from disease surveillance and bat studies and carry wider, messier uncertainty than these ranges. The scoring bands turn continuous data into whole numbers, so different values can tie and small differences can jump a band. The six criteria leave out others a real district would weigh, such as animal welfare, laws protecting bats, and spillover through foods other than pork. This activity has not been tested with students by the authors.

Teacher notes

All totals in the expected observations were computed from the scoring rules exactly; check student matrices first, because one wrong score carries through every total. With the practice weights, A (320) and B (310) are close, which is deliberate: small weight changes swap them, and the worst-case check pulls them apart again. If a group finishes early, ask it to show why A beats B whenever the human-health plus certainty weights exceed the farm-income plus cost weights. Background facts come from the WHO Nipah fact sheet, CDC, and Aziz and colleagues (2017) on flying foxes pollinating durian; the district, its plans and all of their numbers are invented.