Resources & Human Decisions — Investigation · Earth & Space Science, Grade 9
Evaluate resource use and environmental solutions with quantitative evidence and trade-offs.
Choose and Defend a Runoff Design
Investigate
Which feasible design best meets a community’s stated goals?
Plan three teaching sessions: define the model and comparison; run or analyze repeated supplied/collected records; then graph, explain, revise and submit the notebook. These independent home-study routes do not certify the school’s mandated investigations or laboratory minutes.
Materials
- Supplied design estimates
- Calculator
- Notebook
Before you begin
This is a paper-and-data investigation. Use supplied illustrative data or teacher-approved observations. Do not enter hazardous sites to collect evidence.
Plan a fair test
Compare designs for the same site and design storm. Budget is at most 100 cost units; the runoff goal is at most 60 m³. Costs and runoff are illustrative estimates with uncertainty; benefits cannot simply be added when designs interact.
Method
- List the budget, runoff goal, and an additional stakeholder concern.
- Calculate reduction from the 100 m³ baseline for each design.
- Identify designs satisfying both given constraints.
- Choose a feasible design and support it with quantitative evidence.
- Explain a tradeoff and identify an uncertain estimate needing measurement.
- Revise the choice if maintenance capacity is limited; propose a monitored pilot before full adoption.
Open the investigation data (illustrative)
Illustrative data created for this activity; these are not measurements from an actual site or an official reference table.
| Design | Initial cost (units) | Runoff (m³) | Additional consideration |
|---|---|---|---|
| Baseline | 0 | 100 | No change |
| Rain garden | 70 | 55 | Needs vegetation maintenance |
| Permeable paving | 95 | 45 | Needs periodic cleaning |
| Underground tank | 120 | 30 | Exceeds initial budget |
Analyze and explain
- Which designs meet both numerical constraints?
- Compare the runoff reduction of the two feasible designs.
- What evidence could change your recommendation?
- Identify the system boundary, units and conditions held comparable.
- Explain how the graph or figure supports the mechanism rather than merely repeat its trend.
- State one uncertainty or scale limitation and design a follow-up comparison that could challenge the explanation.
What a strong explanation includes
- Identifies which options satisfy both constraints
- Calculates each reduction against the same baseline
- Uses a stated stakeholder priority to justify a choice
- Includes maintenance, uncertainty, and a plan to evaluate results
- Keep observations separate from model-generated or supplied illustrative records.
- Explain a revision using the evidence and a stated model limitation.
Parent / teacher guide: discuss after the investigation
The rain garden and paving both meet the 100-unit budget and 60 m³ runoff goal. They reduce runoff by 45% and 55%. Paving reduces more but costs 25 more units. Either choice can be defended using maintenance capacity, space, and other goals. A pilot should measure runoff across several storms and compare performance with estimates; the lowest runoff option is not automatically feasible. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.