From: Raleigh McLemore (raleighmclemore@yahoo.com)
Date: Mon May 13 2002 - 10:26:39 PDT
Message-ID: <20020513172639.89686.qmail@web13006.mail.yahoo.com> Date: Mon, 13 May 2002 10:26:39 -0700 (PDT) From: Raleigh McLemore <raleighmclemore@yahoo.com> Subject: re: a question on heat
I know that there will be far more complete and
thorough answers to your questions from the other
pinholers but wanted to mention how this question came
up with some fifth graders. We were talking about
evaporation and heat in salt ponds. I was trying to
get them to the understanding that evaporation changes
concentration of a confined amount of sea water and
they immediately started tripping on how the water
evaporates. They dedided on their own that the water
turns to "steam" because it got hot from the sun. When
I asked them if there was any difference between
evaporating water and boiling water they thought about
it and said "only how much water is steaming" and
"boiling comes from the bottom of the liquid" (they
felt that the bubbles that came from the bottom of the
pot made the "steam"). Listening to the three fifth
graders they began to convince me that heating the
surface water molecules was essentially the same as
boiling them in a given volume, but it worried me I
was missing something profound and important by
agreeing with them. I always remember how important
"boiling points" were and I realized that I couldn't
give a clear technical definition of what "steam" and
"boil" (in "Focus on Physical Science" middle school
text it is defined as a "rapid change from a liquid to
gaseous state") mean. Terms such as "boiling", "steam"
and "evaporation" are used many ways, I'm not at all
sure I am using them correctly, but I was so impressed
with the fifth graders digging in on this question.
That's why I look forward to the technical responses
to your excellent question!
With firm handshake,
Raleigh
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