Investigation Station: Science Laboratory - Software - Model It

Investigation Station

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TUTORIAL

I. What is Model-It?
II. Installing Model-It
     A. From a CD
           1. PC
           2. Macintosh
     B. From the web
III. Model-It Tutorial
     A. Acid Rain: Content Information
     B. Introduction to Model-It
          1. Running and Getting Started
          2. Getting familiar with Model-It
     C. Objects
          1. Deciding on Objects
          2. Creating Objects
              a. Using an image in a file
              b. Using an image from Object Palette
     D. Factors
          1. Deciding on Factors
          2. Creating factors
               a. Adding a Factor in the "Plan" stage
               b. Adding a Factor in the "Build" stage
     E. Relationships
          1. Determining and constructing relationships
     F. Testing the Model
          1. Using the Meters
          2. Running the simulation
     G. Saving and Opening Models
          1. Different ways to save your model
          2. Opening a saved model

Relationships

Determining and Constructing Relationships

Relationships are built in the BUILD mode. If Model-It is not already in Build mode, click the BUILD button in the upper left-hand part of the Model-It window.

Determine which two Factors are related to each other. At least two Factors must be present in any model to create a relationship. The first relationship constructed in this model will be between the following Factors: Amount of Sulfur Dioxide and Acidity of Rain. Determine which Factor is the cause and which Factor is the effect. In this example, Amount of Sulfur Dioxide is the cause and Acidity of Rain is the effect.

The first step in constructing a relationship with Model-It is to click on the RELATIONSHIP button in the Build Tools pane on the left-hand side of the Model-It window.

Place the cursor over the Factor that is the cause. Click and hold the mouse button. A red box will appear around the Factor and the label "Causal" will appear above the factor.

Now move the mouse to the Factor which is being affected. A blue box will appear around the factor, and the label "Affected" will appear above the Factor. A long line will also form between the two Factors while holding the mouse button.

The Relationship Editor will then pop up when the mouse button is released.

The Relationship Editor contains many different options. Relationships between Factors are constructed using sentences. On the left side of the Editor there is a sentence that begins "As factory: amount of sulfur dioxide emitted increases, atmosphere: acidity of rain." The pop-up boxes immediately below can be used to complete the sentence in the way that is most appropriate to model this relationship.

Notice that as the pop-up boxes are changed, the graph on the right-hand side is altered to reflect a graphical representation of the relationship.

For this Relationship, finish the sentence by typing "BECAUSE Sulfur dioxide reacts with the moisture in the atmosphere to form Sulfuric Acid." Finally, click on the OK button to save the Relationship.

Notice that the small square on the line connecting the two Factors tells what kind of Relationship it is. In this case, because of the positive slope of the line, the relationship is an increasing relationship.

The first Relationship has been built. Practice by building one more relationship: how coal hardness affects the amount of Sulfur Dioxide. Follow these steps:

1. Determine which two Factors are related.
2. Click the RELATIONSHIP button on the Build Tools panel.
3. Place the cursor over the Factor that is the Causal Factor. For this example, it is Hardness of Coal.
4. Click and hold the mouse button.
5. Move the mouse to the Factor, which is affected and let go of the button. For this example, it is Amount of Sulfur Dioxide Emitted.
6. The Relationship Editor will help determine if View by Text or View by Table is appropriate. For this example,
    View by Text is more appropriate
7. Now, determine if the relationship that is initially set to increase is appropriate. For this example, the harder the coal, the less
    Sulfur Dioxide emitted, so the relationship is not correct. Change the pull down box to decrease by clicking on the down
    arrow on the right hand side and clicking decrease.
8. Adjust other options as necessary.
9. Complete the BECAUSE sentence at the bottom of the Relationship Editor. For this example, complete the sentence with,
    "BECAUSE harder coal emits less Sulfur Dioxide."
10. Click OK to save the Relationship.

The model with three Factors and these Relationships may look something like the following:

Additional Factors and Relationships can be constructed to make the model more complete, or more complex.

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Testing the Model

Once a model contains Factors and Relationships, it can be tested. Testing the model involves manipulating independent Factors to see how dependent Factors are affected. Through the testing of the model and the related discussion it invokes, deep understanding of the modeled concepts is facilitated.

It should be noted that Model-It can not determine if a relationship is appropriate or not. Only through testing and class discussion can such determinations be made.

To test the model, click on the TEST button in the upper left-hand corner of the Model-It window to enter TEST mode.

Using the Meters

The first step in testing the model is to determine which Relationships are to be used in the test. Multiple relationships may be tested at a time. At least one of the Factors involved in the test must be an independent Factor.

Next, click the METER button in the Test Tools panel on the left-hand side of the screen.
Now, click on each Relationship that will be involved in the test.
For this model, click on Amount of Sulfur Dioxide, Hardness of Coal, and finally on Acidity of Rain. A window with a small level control will pop up for each Factor.

Running the Simulation

To manipulate or change the independent variable, "Hardness of Coal", (the factor with no arrows pointing to it), hit the PLAY button in the Test Tools panel on the left-hand side of the screen. Now, the arrow on the horizontal slider bar for Hardness of Coal may be adjusted. The Factors dependent on this variable will also change accordingly. Press the STOP button when the manipulation is complete. Press the REW button to return the Factors to their initial values.

The graphs of the different factors will appear in the Simulation Graph area beneath the workspace. Each different meter will be represented by a line of the same color. As the scales on the different meters change, the lines will also move to reflect the changes.

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