Why We Need Models (Watch the Video Segment)

Model Earth http://learn.genetics.utah.edu/content/earth/

Models are simplified versions of things in the real world. Models help us visualize things we can’t directly observe or easily understand. While models are based on observations and measurements, they always involve assumptions and estimates.

1. List five different examples of models from the video.

2. What examples of models can you name that you have used before?

Pick-A-Model

SCENARIO 1 Choose a 2d visual model to show what causes the seasons. The differences between summer, autumn, winter, and spring are caused by the tilt of the Earth on its axis of rotation relative to its orbit. Earth’s orbit is only very slightly elliptical. If you were looking at it from directly above the orbital plane, it would look more circular than elliptical. It's the tilt that makes it summer in North America when it is winter in Australia.

3. Which model was correct (A or B) and why?

SCENARIO 2 You are designing a new parking lot. This parking lot may need a basin where storm water can collect to prevent flooding. Your city has developed recommendations for how best to model local storm water conditions using a computer model. This modeling tool uses proven mathematical relationships that predict watershed behaviors including storm water runoff. Since storm water behavior in parking lots is well-understood and backed up by lots of data, the computer model's degree of uncertainty is low. Which model should you use to determine if your parking lot needs a basin to collect storm water?

SCENARIO 3 Model how removing a dam would change the shape of the downstream riverbed. A dam that was built in 1910 is no longer needed for hydroelectric power, and its removal will restore migratory fish habitat. You want to test different strategies for removing the dam, which holds millions of gallons of water and many years of accumulated sediment. Releasing the sediment too quickly will overwhelm the system. Releasing it too slowly will increase the cost of the project. Dam removals aren’t very common so there is little historical data to draw from. Riverbeds contain a complex mix of different materials—including sand, gravel, and mud—that are difficult to represent numerically. Which is the best model to use for dam removal?

SCENARIO 4 Pick a flood-risk predictive model that city officials can use to prevent flood damage. A small city next to a river is at risk of flooding this spring. A levee protects the city from floods up to 51 feet; it has never been overtopped. However, snowfall this winter was higher than any on record. Officials want to use a predictive model to determine whether to deploy flood prevention measures like sandbags. Lack of comparable historical data means the predictive model will rely heavily on estimation. Which model works best to plan for a potential flood?

What can you do with Models We can use models to show, explain, recreate, and predict. When we use multiple models to approach a problem, we get a more complete understanding. For each of the following sections, list 3 different applications for each.

Show Form and Function From life-size robotic dinosaurs to an inventor’s patent drawings, models help us see how things work. 7.

Define a System A system is a set of related elements that come together to form a functioning whole. Models help map the relationships that make up systems. 8.

Simulate Something A simulation is a model that looks at how a system changes over time, often under varying conditions. 9.

Make Predictions Natural events often follow patterns. Predictive models use what we know about the past to forecast the future. 10.