Describe one cycle, map how it moves through an ecosystem, and show where human activity changes it.
Here's what's on deck. Check Canvas for full instructions and submission links.
Objective. Describe a major biogeochemical cycle and analyze its interactions with human activities to evaluate its role in supporting Earth’s life-supporting systems. Final deliverable: a single, cohesive visual illustration (created collaboratively via Zoom Whiteboard, InsightMaker, Miro, Canva, PowerPoint, or a similar platform) divided into three clear sections: Title, Diagram, and Summary.
Pick one cycle: The Nitrogen Cycle · The Phosphorus Cycle · The Carbon Cycle · The Water Cycle · The Oxygen Cycle
Context: ground your diagram in a specific geographic context. You may base it on the local Sonoran Desert (Phoenix area), or select a comparable ecosystem (e.g., tropical forest, temperate forest, savanna) if it provides a more compelling case for your cycle.
A clear, descriptive title that names your cycle and your chosen ecosystem.
e.g., “The Nitrogen Cycle in the Sonoran Desert”
Map the complete cycle by explicitly annotating the pools, inflows, and outflows. Use boxes or circles for stocks, labeled arrows for flows, and icons or clipart to highlight human touchpoints.
Key components (stocks / pools): the main reservoirs where the element resides (e.g., atmosphere, soil organic matter, vegetation, microbes, water bodies).
Key processes (flows): the essential biological, chemical, or physical processes that move the element between pools (e.g., photosynthesis, nitrogen fixation, nitrification, decomposition, erosion, evaporation).
Human impacts: integrate 2–3 human-caused disruptions to the natural cycle. A Nitrogen team might illustrate fertilizer runoff, fossil fuel combustion, or soil crust degradation; a Carbon team might focus on vehicle emissions, deforestation, or urban concrete replacing biomass storage.
Synthesis statement: a brief, original summary analyzing the cycle’s unique dynamics within your chosen ecosystem.
“In the arid Phoenix desert, natural nitrogen cycling is highly limited by moisture, making biological soil crusts crucial for nitrogen fixation; however, urban fossil fuel combustion heavily amplifies local deposition…”
Collaboration: work actively with the students around you. Individual submission: take a high-resolution screenshot or export your final work as a PDF. Every student must upload their own copy to the Canvas link to receive credit.
Student self-assessment checklist. Before uploading your file, verify that you can answer Yes to all of the following.
Did you map and clearly label all major stocks, pools, or reservoirs?
The builder’s panel ticks this at three or more stocks, every one named.
Did you explicitly show the directional processes and flows using clear arrows?
Every flow piped to a stock, and named after its process.
Did you illustrate and explain at least two concrete human impacts or disruptions?
Two human impacts on the diagram, each explained in Summary.
Is your diagram grounded in an appropriate, clearly identified ecosystem context?
A cycle and an ecosystem chosen in the title band.
The same marks work in InsightMaker, Miro or Canva. Watch Dr. Pavlic’s tutorial for the causal-loop half.
Every student uploads their own copy on Canvas: a high-resolution screenshot or a PDF. In the builder, Save as PDF makes that file, and Save keeps a copy of your work you can open again later.
The bottom section of your deliverable. It prints beneath your diagram.
A qualitative sketch, not a measurement. Every pool starts at 100% of its own size, each process runs at the speed you gave it, scaled by how full its source is, and a + or − arrow into a process speeds it up or slows it down. Solid lines include your human impacts; dashed lines leave them out.
The builder makes the single illustration the assignment asks for, in its three sections: the Title band across the top, the Diagram on the canvas, and the Summary you write in its own window. Save as PDF prints all three on one sheet.
| Stock | A pool or reservoir where the element sits: the atmosphere, soil organic matter, an aquifer. |
|---|---|
| Flow | A process that moves the element from one pool to another: fixation, decomposition, runoff. A cloud at either end means the material comes from, or goes to, somewhere outside your system. |
| Condition | Something that speeds or slows a process without being a pool itself: rainfall, temperature, microbial activity. These are the variables of a causal loop diagram. |
| Human impact | A human touchpoint, drawn with its icon. A flow can also be marked human-caused in its editor, as fossil fuel combustion would be. |
⇒ Flow draws a whole process in one drag. From one stock to another, it adds the valve and both pipes. From a stock into empty space, the material leaves the system. From empty space onto a stock, it enters from outside. You can also drop a process from the palette and pipe it in afterwards.
+ Arrow and − Arrow draw causal links. A + means the two move the same way (more rainfall, more leaching); a − means they move in opposite ways. Point arrows at a process to show what speeds or slows it. Clicking an arrow flips its sign.
Double-click any piece to rename it (suggestions for your cycle appear as you type), mark a flow human-caused, or explain a human impact. Delete removes a selected piece, and Undo takes back the last change.
The panel names every feedback loop it finds. Pipes count: an inflow raises its stock and an outflow lowers it, so an arrow from a stock to its own outflow closes a balancing loop. ▶ Run the model plays the diagram forward and compares each pool with and without your human impacts. It is a sketch for thinking with, not a measurement.
Everything saves in this browser as you go, so a refresh loses nothing. Save downloads a .cycle.json file you can Open later on any computer, or send to a groupmate. Save as PDF makes the file you upload to Canvas; every student uploads their own copy.
The worked example is the sulfur cycle, which is not one of the five on the assignment, so it shows the shape of a finished answer without being one.