During the height of last summer's heat wave, my neighbor Dave knocked on my door.  He seemed upset, so I asked him what was wrong.  Dave said "I can't understand what's wrong with my new screen door!  It's stuck shut!"

    Dave's old, worn out screen door allowed cold winter drafts into the house, so he replaced it with a brand new aluminum screen door in the middle of winter.  He made sure the door fit snugly into the frame, with only .001" of clearance between the door and the doorjamb, and was pleased that he didn't get any more cold feet on his midnight refridgerator raids.

    Today, in the middle of the worst heat wave in a decade, when the meterologist said the temperature would climb above 100 degrees, Dave decided to open all the windows and doors in his house to allow the heat to escape.  When he went to open the new screen door Dave wasn't able to open it!
 
  

    "I think the change in temperature affected my door, but how did it make the door stick shut?"  Dave asked.  I told him I didn't know, but that I would present the problem to you.  "Make sure that everyone else knows what happened, so this won't happen again!" he said.

    Why did Dave's door stick shut?  Was it the temperature?  Could it have been due to a change in the humidity?  What else could have possibly changed between the time it was installed and this morning?  It's up to you to investigate!

    I've prepared a data sheet (right click on the link and "Save Link Target As" on your computer) for you and your partner to investigate and record the effect that the change in one variable has on a sample of aluminum.  Please provide a detailed description of the sample of aluminum you and your partner are using to represent the screen door.  Temperature, per Dave's request, is the variable listed on the data sheet, but if you think another factor may have caused Dave's door to stick shut, please check it out.  Design your experiment to alter your chosen variable in such a way that no other variable is affected in order to test your hypothesis.  Provide the details of your procedures in the space provided on the data sheet.

    After you and your partner have experimented with your sample, and collected your data, please graph your data points.  When you've finished your graph, present your information to your classmates.
 

    After everyone in your class has presented their information discuss why a change in any of the variables might have caused a change in the door.  Also, are there any other reasons that the door may be stuck shut?  Listed below are a few web sites that may help you with your analysis.

   
    Now that you and your classmates understand what happened, and why it happened, please present your findings to the world.  The fastest way is to place all of your information on the class's web site, which can be accessed by anyone interested in learning about some of the pitfalls of an aluminum screen door.

    With your lab partner, prepare a description of your procedures, data, graph, and conclusions to be placed in your section of the web site.  As a class, develop an introduction stating the problem, and your class's final conclusion of what caused the problem, and why.  Finally, with your partner, find a screen door manufacturer or installer, and email them the URL of your class's web site so that this doesn't happen again!