HOMEWORK #1  Models

(see Syllabus for due date and points possible)

Locate a news article less than 9 months old describing some phenomenon that pertains to the scientific method (on any topic, not necessarily biology or the "natural" sciences). From the description contained in this article, identify TWO models of different kinds (physical, abstract) and fill in our model template for each of these models, as given below.

Detailed instructions for the "ideal" homework assignment follows, which should be followed as closely as possible when filling in the writeable Word assignment form. For each feature of the model template, the type of answer that is expected is indicated. Especially note that

i)               your work needs to be typed responses in the Homework1 writeable Word form

ii)             the article must be less than 9 months old

iii)           upload the article along with your filled Word template on your BbLearn account for this class; if your template has a link to the article, you do not need to upload the article separately. If you need to upload the article, upload both files to BbLearn (during the same submission)


Objective: You are going to identify two models of different types, the goal for which they are used, and the limitations of those models for that goal.  You will also need to identify the kinds of models they are.   This assignment is fairly easy, but one potential difficulty is in making the proper connection between the goal, models, and limitations – your work needs to indicate how all 3 are related to each other. 


How to use the Models Word template

Name: Type your name in the field.

Article: Give the link.  If no link is active, upload a scan, pdf or html file of it. We want to be sure we have access to the article, so a little redundancy does not hurt. In the next field the title, source, and date of the article.

GOAL: (you may use the same goal for both models)

Describe the goal for which the model is being used. This can be confusing because there are often many angles that you can approach the information in an article, and the goal may depend on the angle.  Remember that you are trying to develop a thread between a goal, a model, its use and its limitations.  Any consistent thread works.  For example, in testing condoms, the goal (of the government mandating the test) is to evaluate condom integrity for sex.

But consider an advertisement you see in a magazine as your model.  The goal of the advertiser might be to discover ways of improving product sales. You would then fill out the model as the ad, its use (by the advertiser) is to get sales, and its limitations could be any way in which it misses out on sales.  You can thread all of those together from the goal.  But consider instead that you are the one looking at (using) the advertisement.  Your goal might be to gain some useful information (e.g., learn about a sale that is described).  The ad is once again the model, but its use now ties to your goal – get information of interest to you.  And the limitations also now change because of the different goal: for example, the ad might omit some important qualification, or it might present a more favorable view than is reality.  You can again develop a consistent thread from goal to model to limitations, but it is a different thread that stems from a different goal.  You ONLY NEED to develop one of these threads (for an abstract model, one for a physical model). 

If both of your models are used for the same goal, you only need to list the goal once.  However, you need to fill in the rest of the template for two models (of different types), as follows.  In general, the goal should not refer to the model.

Note:  Using and understanding two different models is critical to this assignment.


First MODEL (you will answer the same questions for the second model):

In one sentence or less, state the model you are identifying. For example, if the model is a hypothesis, then simply state the hypothesis. Or, if you have chosen a physical model, then just write what it is (e.g., mice, map, DNA, ...).


USE -- A model of what? (What does the model represent?):

Explain what the model is used as, or is used to predict or to explain. In the step above, you identified what the model IS; here you should explain what it is a model OF. For example, rats may be a model of humans (or, more specifically, cancers in rats fed saccharine may be used as a model of the cancer in humans fed saccharine). A computer simulation of global warming is a model of the process of global warming. The hypothesis, "Latex condoms prevent the spread of HIV", is a statement that explains how to avoid infection by HIV. The equation E = mc2 may be used as an abstract model of the physical relationship between energy and matter. The application or use of a model does not mean that the model is particularly good or bad at this purpose, only that it is intended to have this purpose. The use of the model should fit closely with the goal.


of What?

"Latex condoms prevent the spread of HIV"  (a statement or hypothesis)

ways to avoid contracting HIV; or ways to advise people to avoid contracting HIV (depending on the goal)

A laboratory rat


10,000 cancer patients in the U.S.

all U.S. citizens with cancer

A computer simulation of global warming

the process of global warming

E = mc2

the relationship between energy and matter

a correlation between teen pregnancy rates and high school sex education course content in Texas in 2004

a model of factors possibly influencing teen pregnancy rates (sex education), also a model of teen pregnancy rates and sex education in previous years and in future years

the car you test drive at the car lot

model of the car you would buy

Newspaper headline

model of content of the article



Using complete sentences, identify one major limitation of the model (a way in which the model is false). This limitation should either be given in the article or be your suggestion, but you should identify an important limitation as opposed to a trivial one. Note that we are asking for limitations of the model you identified as that model is used for the goal you identified.  Limitations of a model are usually not limitations of the study described in your article. Here are some examples:

"The article indicates that a substantial subset of the scientific community feels that the 10,000 cancer patients used in the smoking study were not very representative of all humans because they were all male. Women may respond differently than men to cigarette smoke."

"According to the article, the computer simulation used to predict future global warming patterns ignores the effects of future volcano eruptions. Therefore, as Dr. Seuss states in the third paragraph of the article, the simulation may exaggerate increases in temperature over the next 100 years."

To reiterate what was noted above: the goal, use, and limitation should be integrated closely with each other. Since the goal determines model usefulness, the use of the model as well as the limitations should all be focused around the intended use or purpose of the model. Thus, if condoms are tested to predict how they will hold up during sex, the airburst test becomes a model of sex and the limitations are that the airburst test does not closely represent sex.

Recongizing limitations of an abstract model, such as a hypothesis, may be more challengeing that identifying limitations of a physical model. With a physical model, such as a mouse as a model of humans, the limitations are obvious because we can SEE the difference. But an abstract model is more difficult to grasp as a model, and its possible limitations are especially difficult to contemplate when the abstract model is being tested and might even be rejected by that test (in which case it has major limitations but you don't necessarily know them yet). For this case, the easiest solution is to imagine that the model is not rejected; then merely consider limitations that apply even though the model otherwise seems OK.


A one-word answer. Simply write "abstract" or "physical".


Second MODEL:

Now fill in the same template for a second model from the same article. This model should be a different type than the first. Thus, if the first was an abstract model, the second should be physical.

Copyright 1996, 1997 Craig M. Pease and James J. Bull. All rights reserved.