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First Systems Diagram
Have students develop a preliminary diagram or “concept map” highlighting important factors affecting their state variable (particularly those factors that directly cause the trends shown in the “problem” and “solution” graphs.)
Through her library research, Kendra has learned that there are many threats to coral reef health. Among them:
- Physical damage from boat anchors and careless scuba-diving tourists.
- Hurricanes
- Water pollution
- Smothering by excess sediment coming from rivers
- Dynamite (people use dynamite to stun fish for food or to break apart the reef to collect sea shells)
- Coral “bleaching” and death associated with increasing ocean temperatures.
Her first diagram uses arrows to indicate that these threats influence coral reef health. The arrowheads indicate the direction from cause to effect. She has used little minus signs by each arrowhead to show that, in each of these cases, the cause and effect are inversely related. For example, if anchor damage increases, coral health decreases. If anchor damage decreases, coral reef health increases.
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