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Published byCaroline George Modified about 1 year ago

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Overarching Goal: Understand that computer models require the merging of mathematics and science. 1.Understand how computational reasoning can be infused into teaching. 2.Develop a working definition of computational reasoning. 3.Recognize the importance of graph interpretation skills in understanding model behavior. 4.Recognize that probability and random numbers are important mathematical ideas that can be modeled using tools of computational reasoning. 5.Understand that probability can be used to simulate real-world phenomena and make predictions.

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1. Why computational reasoning? 2. Probability – theoretical vs. real-world behavior 3. Probability in an agent-based model 4. Probability in a systems-based model 5. Analysis of model output via graphs 6. Comparison of agent-based and systems- based models 7. Curriculum applications

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Understanding how to analyze, visualize and represent data using mathematical and computational tools Using computer models to support theory and experimentation in scientific inquiry Using models and simulations as interactive tools for understanding complex concepts in science and mathematics

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Addresses Common Core Standards in Mathematics Standards for Mathematical Practices MODEL WITH MATHEMATICS Reason abstractly and quantitatively Use appropriate tools strategically Look for and express regularity in repeated reasoning Standards for Mathematical Content Making Inferences and Justifying Conclusions o Understand and evaluate random processes underlying statistical experiments o Make inferences and justify conclusions from sample surveys, experiments and observational studies.

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Supports teaching science as inquiry by providing: Models of real world events that are difficult to demonstrate in wet lab experiments Opportunities for careful observation and analysis of scientific investigations The ability to test hypotheses, analyze results, form explanations, judge the logic and consistency of conclusions, and predict future outcomes.

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Theoretical probability vs. the real world 1.What is the probability of getting a head when you toss a coin? 2.In 10 trials, will you get an equal number of heads and tails? 3.In 1000 trials, will you get an even split? 4.Will everyone in the room get the same answer? 5.How would you design an experiment to answer these questions?

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Since probability is usually expressed as a fraction between 0 and 1, a computer uses a formula that will generate numbers between 0 and 1 in no discernible pattern – we call these random numbers. To simulate flipping a coin, we make the rule that numbers less than ½ represent heads and numbers more than ½ represent tails. If thousands of numbers are generated, approximately half of those numbers should be less than 0.5 and the other rest should be greater than 0.5 If only 10 numbers are generated, will half of them be less than 0.5? Try this out using the interactive Excel spreadsheet.

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Open the flipping_pennies.xls spreadsheet. Answer the questions on the handout.

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After conducting the simulation, consider these questions. 1.Will a simulation that uses random numbers give the same result every time it is run? Explain. 2.Is such a simulation a valid representation of reality? Explain. 3.What can you learn from a simulation if it doesn’t always give the same result? Explain.

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Using an agent-based forest fire simulation to explore: Probability Random Numbers Averages Predictions and Hypothesis-Testing Assumptions

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What could we learn by observing this simulation? What should we look for?

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Open Set the burn probability in the Probability box. Click on any tree to start the fire. Note the percent of trees burned. 1.Does the percent of trees burned stay the same for a given burn probability? 2.Does the location of the lightning strike affect the percent of trees burned? 3.What does the value of a burn probability mean?

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What could we learn by observing this simulation? What should we look for?

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Question: How do you think the percent of trees burned is related to the burn probability? Experimental Design: Get in groups of four to design an experiment. Share your experiment with the class.

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Question: How do you think the percent of trees burned is related to the burn probability? Procedure: Using the burn probability assigned to you, run the simulation 10 times and average your results. Share your average with the class to create a comprehensive data set. Sketch a graph of percent burned vs. burn probability.

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Questions: How realistic is this simulation? What are its limitations? Name some other factors that influence the spread of a forest fire.

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What is similar about the two simulations we have run today? What is different about the two simulations we have run today? How might this impact your teaching about the concept of probability?

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Uncertainty in the real world can be modeled using random number generators. (Goals 2, 4 & 5) Model outcomes will vary when random numbers are used to model probabilities, but trends can be observed through graphs of data collected with multiple runs. (Goals 1 - 5) The assumptions behind a computer model must be made explicit to understand the model. (Goal 2) Computer models can be used to challenge your preconceptions. (Goals 1 & 2)

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Using a systems-based model of a forest fire to explore: Probability Graph Interpretation Patterns in Model Behavior Predictions and Hypothesis-Testing Assumptions

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Lightning strikes a tree in the forest. Other trees, depending on their location and their condition, can catch fire from that tree. The number of newly burning trees depends on ◦ the burn probability ◦ the number of burning trees ◦ the number of non-burning trees that come in contact with the burning trees Burning trees eventually cease burning and can no longer spread the fire.

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Open the ForestFire.mdl model. Run the model. Predict how the graph would change if 1.you increased the burn probability. 2.you increased the days to burn.

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Run the model In AutoSim mode. 1.How does the forest fire change as the burn probability is changed? 2.Do your neighbors get the same result you do when you all use the same burn probability? 3.Is there any evidence of random numbers in this model? 4.How does the graph change when days to burn is increased? 5.How does the number of days to burn change the behavior of the forest fire?

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What is similar about the two versions of forest fire simulations we saw today? What is different about them?

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Theoretical probabilities can be used to calculate the behavior of a group of objects in a model. (Goal 5) Models can be used to test predictions about the behavior of a system under varying conditions. (Goal 5) Graph interpretation requires an understanding of both axes, the shape of the curve, and the underlying model. (Goal 3) The same problem can often be represented in both agent-based and systems- based models. (Goals 1 & 2) Problems that seem different on the surface may have characteristics in common when looked at from a modeling perspective. (Goals 1 & 2)

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List topics in your curriculum that involve… Random behavior Probability Interactions between individual agents Changes in aggregate behavior over time Examples Biology/Environmental Science – predator/prey, epidemics, genetic drift, food chains, ecosystem disturbances Chemistry – enzyme kinetics, gas chromatography, heat, diffusion Physics – mechanics, radioactive decay Earth/Space – climate change, erosion, percolation Mathematics – fractals, random walks, probability

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