Description of Activity/Phenomena:
    There is a sealed tube that has four holes poked in it.  The holes have thread, tied at the end, in them.  When any of the four knots of thread in pulled, it pulls the thread from the other holes into the tube so that just the knots are on the tube.  The tube then has one string hanging from the side, the one which is pulled, while the other holes are blocked by the knot in the string, but no string is hanging from the tube.  If the string in another hole is pulled out, the string that was hanging out pulls in.  All that can be seen is the outside of the tube; it is sealed so that no one can see inside it.  After seeing the Mystical Tube, students are to make up their own working tube (create their own model of what the tube looks like on the inside).

Typical Observations:
    *Tube is rather light, does not seem like mush extra inside the tube
    *No matter what string pulled all of the others go into the tube
    *All strings pull into the tube completely, when one is pulled.  No part is left dangling
    *Could be anything inside tube.
    *Many different plausible looks for the inside of the tube
    *Never know for sure what the tube looks like on the inside because it cannot be opened.

Explanation:
   Who knows what is on the inside of this tube?  We cannot see it just like we cannot see what the inside of an atom looks like.  Everyone in a class will not come up with the exact same idea of what the tube looks like on the inside, but their ideas will still work.  Which model is correct, no one knows because you cannot see inside the tube so we cannot prove any of the models wrong.  If one model does not work like the tube does, then we know that one is incorrect because it does not correctly predict what we see.
    This activity shows the uncertainty of models.  We can never be sure whose model is correct but if they work and help us understand what we are looking at, then it is a good model.  We can never be sure what an atom looks like because we can't see inside it, it is too small, but we can create models of what the atom.  If the models we create helps us understand the other phenomena from the atom that we see, like atomic spectra, then the model is good.  Just like our model of the Mystical Tube can never be certain, neither can our model of the atom.

To learn more about student's ideas of models which this activity is meant to clarify and hopefully correct any incorrect ones, please click here.

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