The first thing to recognize is that 0° Fahrenheit is pretty cold, well below freezing.  Is there anything that happens on a pretty regular basis that is this cold?  There is a clue in the simple act of spreading salt to melt icy patches on your steps or sidewalk.  I’ve always been puzzled by this.  Spreading sand made sense.  It simply provided a grip for your step.  But salt isn’t going to lower the temperature.  How could it melt the ice?  It turns out, and you can try this at home, that salty water needs a colder temperature to freeze than clean water.  When we throw salt onto ice, we’re counting on the smallest crystals of salt mixing with odd bits of liquid water and so the surrounding ice finds itself not cold enough to stay frozen.

So, we may ask, at what temperature does salt water freeze?  It turns out that it depends on how salty the water is.  But if we use a salinity like that of ocean water, a sort of natural saltiness, then it freezes at 0°.  Pretty sweet.

With this as a baseline, Fahrenheit then looked around for a second ‘natural’ temperature.  What temperature would everyone have ready access to?  A clue is a temperature pretty close to 100°, the 98.6° of body temperature.  Fahrenheit had actually called this 100 and not 98.6.  His temperature scale had originally been a centigrade scale!  When scientists decided that freezing clean water was more reliable than the vagaries of ocean salinity and that the boiling point of clean water would be another equally secure and reproducible temperature…which happened to fall at 212°…that shifted things a bit and the ‘normal’ temperature for most of us most of the time became 98.6.

Reason restored.

What’s going on here?  Why would the water go down, when you add heat?  It takes a moment, but then kids realize the thermometer is upside down.  That it is really “rising” when the water goes down.  Now another problem arises…what is the thermometric fluid? That is, what is the substance that is expanding and contracting with changes in temperature?  It’s the air above the water.  The water is just there so that we can keep track of the changes the air is going through.  This is a neat realization, and students suddenly appreciate the mechanics of thermometers in ways they hadn’t before.

Next, we take the temperature of different items.  We first mark where the water level is.  Then we take the temperature of our hands.  How far down did the water get pushed?  Curiously, it won’t be the same for everyone.  Most of the thermometers in the classroom are quite different from one another and even though there is no reason to think the air trapped in the bulbs is any different, how much they rise and fall is largely a function of the proportions of the glassware.  The one thing they have in common is the starting point: for each thermometer, that is room temperature.  But that means the next day, the base line may well have moved.  The room may be warmer and so the water would drop less with your hands.

What we need is a temperature scale that could standardize measurements.  That’s the problem Fahrenheit solved.

We all know that the Fahrenheit scale is marked by those curious numbers, 32° for the temperature of freezing water and 212° for the boiling point.  But who would make a scale that runs from 32 to 212?  No one.

Years ago I was in a small town in England on the North Sea, Aldeborough.  It was a typical Spring day, cold and damp.  After walking a while along the pebbly beach, Roy suggested we head into town for a cup of tea.  That sounded like a good idea, so we turned our backs on the water and walked up to the road that ran parallel to the shore.  As we crossed, I noticed it was 7^th street.  I mention this because as we walked up the High Street the nest street was not 6^th but 8^th.  Who would lay out a town starting with the number 7?  No one.

I turned to Roy, our English friend and asked him what was up.  He smiled and asked me to look out into the inlet.  I was stunned to discover the tops of a couple of buildings quite a ways out into the water.  Aldeborough, an old town, was giving way to an encroaching sea.  First street was out there.

So, borrowing the morale of this tale, can we re-construct the rationale of the Fahrenheit scale?   It, too, was a centigrade scale.  Can you figure out what 0° Fahrenheit would have been?  Or 100°?

At the end of World War II there were hundreds of thousands of unaccompanied children, described by one aid worker as “tired, wan, broken little old men and women,” who had forgotten or never knew how to play.

Sometimes these children were brought together in large camps, but most often they were separated into enclaves by nationality or ethnicity.  There was an issue of “indoctrination.”  Who has the right to teach the “right” cultural setting for such children?  Such concerns even led some to distrust that families would teach these children properly and advocated instead for communal arrangements, where children would live in an extended family of a children’s facility or kibbutz.

One aid worker with the UN testified to the hope and long hours spent “on individual children…endeavoring to revive their love for their family and country.”  Often, postwar nationalists, psychologists and workers for international charity organizations were given to bouts of frustration and despair, fearing that these children were neither malleable nor innocent.  From a different perspective, Anna Freud wrote:  “It is a common misunderstanding of the child’s nature which leads people to suppose that children will be saddened by the sight of destruction and aggression.” Far from being traumatized by such experiences, children were as likely to be scintillated by them.  “If we observe young children at play, we notice that they will destroy their toys, pull off the arms and legs of their dolls and or soldiers, puncture their balls, smash whatever is breakable, and will mind the result only because complete destruction of the toy blocks further play.”

Europe’s lost children were not only cherished as the hope of a new and brighter future, but also feared as the totalitarian henchmen of tomorrow.  One official with the largest Jewish child welfare organization ran a home for ‘Buchenwald boys’…boys who had survived the camp, one of whom was Elie Wiesel.  The official characterized them as “true psychopaths, cold and indifferent by nature, and that this was the reason they were able to survive.”  Others used such sentiments to argue against allowing these children to immigrate…the refugees had experienced trauma that was irreversible and would undermine the well-being of society. …

My imagination can give place to such fears; just as I can picture these children as needing nothing so much as love and the chance to be children.  There is a contradiction in policy, perhaps, but the human condition is full of such contradictions.  What would I have done?  Can I fear and offer love at the same time?  Is that what is called for?  What about respect and the invitation to join a common cause?  “There is a place for you,” I might say. “What do you think?”

A typical set-up uses a flask at the top with a one-hole stopper and a length of glass tubing running down to a beaker of water.  I would usually put out a range of options: Erlenmeyer and Florence flasks of different sizes, different lengths and diameters of tubing, and different sizes for the beaker at the base.  A former student who did this lab with his middle-school classes devised a delightful inexpensive and low-tech variation that is just fine.  It uses a small glass bottle, like a ‘Veryfine’ juice bottle.  Drill a hole through the plastic cap large enough for a transparent straw, and then use glue to seal the fit of the straw.  A plastic cup works just fine as a beaker.

The next step transforms the glassware into a thermometer.  First put water into the beaker so that the tubing (or straw) is standing in water, though not touching the bottom of the container.  By the way, you should put some food coloring into the water to make it easier to see.  We want the water to stand about midway up the glass tubing or straw.  Ask students how they might get this to happen.  They might come up with a good idea or two.  If not, ask what would happen if you heated the air in the flask or bottle at the top.  You might try it with a set-up of your own.  The air expands as it’s heated and pushes its way out the only opening…the bottom of the glass tube or straw.  If we used a candle to heat the flask and then pull it away, the air can now cool.  What happens now?  The air will contract and the water will rise up the tube.

This is a great time to talk about vacuums, and the difference between seeing a vacuum as sucking things up and surrounding air pressure as pushing things in.  I would usually offer the plausible maxim that “nothing is not an agent”.  If there is nothing to a vacuum, how could the nothingness actually pull anything?  This conversation would itself lead to all sorts of notions and side explorations with a vacuum pump.

But, let’s get back to the thermometer.  If you have guessed how much air escaped by counting bubbles, for example, and it was a good guess, the water will stop near the middle of the tube, and now you have a thermometer!  That is, you have a device that is sensitive to changes in how hot something is, but at which end?

But let’s leave this for next week…

The first thing we do is try to make a fire.  It turns out to be really hard. Students try rubbing sticks to together and it never works.  Even when they push things by making fire bows to increase the speed of the ‘drill’, it fails.  They also try striking flint to get sparks that would catch tinder and cause it to light.  These, too, always fail, though you can get some things to char a bit; unless you are very careful about your materials.

Magnifying lenses are much more successful, but glass-making requires pretty sophisticated fires; so clearly, this was not how fires were made early on.  The moral of these efforts is that fires were so difficult to produce and yet so valuable, that ancient peoples would have worked very hard to make sure they did not go out.  To keep the flame going would have been of paramount importance.  As we discussed earlier in this essay, so great was its import that civil society itself may well have been the consequence, not to mention the central role of fires on the altar and the emergence of the priest as keeper of the flame.

Once we have done this, the next question we explore is the difference between heat and hotness.  That there is an issue here is made delightfully clear with a simple experience.  Get three bowls of water.  To the left is a bowl of cold water, on the right –hot water.  In the middle put a mix of hot and cold, lukewarm water.  Now place your left hand in the cold water and your right hand in the hot water.  Let them acclimate to the feel of the two bowls and then put both hands simultaneously in the middle bowl.  Your hands will give you conflicting signals…your left hand will say the water is hot, your right hand will say it’s cold.  Since we have every reason to believe that the water doesn’t care how hot or cold your hands had been before and that it is what it is, we conclude that hands are not a good measure of what’s going on with the water.  We also begin to see that there is some quality to the water that we are seeking that has to do with degrees of hotness.  Hence the need for a thermometer…our next lab.

Not long ago I sat with a bunch of students from different parts of the country, urban and rural, white, black and Hispanic.  They came from troubled communities and troubled schools.  We started with several activities to break the proverbial ice, including one where students paired off, interviewed one another and then with the whole group back together, they introduced their partner.  I was struck by the number of times they got it wrong.  They had the wrong name for their partner or her school, or maybe they got the name of a favorite movie wrong.

Why?

I’ve been a high school science teacher for over 25 years.  I had long been prepared to expect that I might not be understood; so when I started to work with inner city kids, I worked hard to engage them in conversations so that we could all be on the same page.  When a student offered a comment or question that I did not understand, I would apologize and ask him or her to please say it again.  They were patient and put up with this old guy.

I assumed that any trouble I had understanding them came from the linguistic/cultural distance between us.  But when so many kids were getting it wrong that afternoon, I started to see something else.  There were few linguistic/cultural divides amongst these kids.  They were the same age, immersed in the same pop culture and the same poverty.  Why did they not get it right?  Perhaps, these kids were not speaking to one another with the confident expectation that they would be understood…

Certainly, if we learn to look one another in the eye; if we learn to weigh our words and take their measure from the reaction we get; if we are empowered by that reaction, then when that doesn’t happen, perhaps we learn a different lesson…perhaps we learn to get by, to cope with less than clarity.

Another Anecdote:

Hans Furth, the author of Thinking Without Language (1966), a book about the deaf, was fond of making this observation:  that of all the natural groups within American society, groups defined by profession, by race, religion, etc., the healthiest mentally were the deaf.  Why would this be so?  Why would being deaf mean you were less likely to suffer from schizophrenia or to be institutionalized?  The answer he favored had to do with the sign language.  The argument goes like this…

The gestures of the sign language are everywhere complemented by facial expression.  This is because the signs themselves are open to interpretation that is completed by cues for intensity and the like which come across via the eyes, a nod of the head, etc.  For example, there are several words in English which indicate degree of obligation…ought, should, must.  But in the sign language, there is just one sign…you crook your index finger, somewhat like the way you might hold a pencil.  You indicate the degree of obligation by the intensity of the gesture, ranging from a slight pecking motion to an emphatic sweeping motion. As a result, the deaf look at one another squarely as they talk.  At the same time, as a speaker, you are more energetically committed to what you are saying and so it is difficult to deceive.  That is, the deaf are more straightforward with one another, which contributes to good mental health.

Talk is healthy; it’s important, and for too many it is not happening.  We know, for example, from considerable research that low-income children start to lag behind in vocabulary growth compared to middle class children by the age of three.  It is not a matter of exposure to the spoken word.  Having a television on in the background doesn’t do the trick.  There’s got to be a real person in the room.  But even here there is an important caveat.  It is not the amount of talk children are exposed to.  That is, children of low income parents who were very talkative still lag behind their middle class peers.  In their study, Pan et al (2005) point to a couple of considerations, most especially the degree of negative talk.  Low income parents used more prohibitions, discouragements, and directives than middle or upper middle class parents.  Such considerations heighten the importance of talk for school aged children, but we are sorely disappointed when we visit school classrooms where all too often we find a steady pulse of the wrong talk…talk with just this negative quality; talk that is about doing what you are told.

Anecdote number three:

            Back when I was in graduate school I found myself teaching at the University of Leeds for a year.  I had a lovely time.  Here are two of the more important stories I brought back to the States with me.  One came from the grading form used by the university, where students were listed in two columns as either regular or mature.  Intrigued, I inquired as to what constituted maturity and learned that it referred to those who has interrupted their trajectories as students and had gone off to work or perhaps to travel.  Presumably the university felt that such students returned to their schooling with a greater appreciation for their studies.  A perceptive judgement.

The other story is also about schools.  A senior professor at Leeds took me under his wing.  He was a lovely guy and I can still recall many of our conversations.  One morning as we walked to school he told me about a television program the evening before, where reporters interviewed students from the Westminster School.  Westminster is what we would call a private or independent school and can trace its history all the way back to the late 12^th century.  What Jerry Ravetz had found so striking was not that these young men and women were so bright, but how they took it as perfectly natural that adults would be interested in what they had to say.  This is the complement to what I had seen with students from troubled schools.  I have no doubt that we come hard-wired for language, á la Chomsky’s deep structures, but evidently our capacity to connect to people and to speak directly is learned.  So much of what we become is formed by the interest, or neglect, that others exercise.

Anecdote four:

Let’s look at the standard approach to classroom management.   Class time is choreographed.  Students come in and a warm-up task or drill is on the board, along with a timer that is projected.  Students have five minutes, make that four minutes and fifty-five seconds, to finish this assignment.  Meanwhile the teacher works the room, checking off those who have their homework.  When the five minutes has elapsed, these papers are passed forward and students retrieve books from the back of the room.  They are to read the first four pages of chapter 6.  The timer shows ten minutes.  Then they collect into small groups and work on certain problems.  Time again directs the dance.  An entire hour and a half is consumed this way, with nary a moment for a group discussion.  There are worksheets, exercises like coloring the nucleotide sequences of a stretch of DNA, or labeling items on a map of Europe in the 15^th century.  But there is no talk, no utterances that are whole thoughts or sentences strung together to explain a point of view or to frame a question…save the occasional request for permission to sharpen a pencil or go to the bathroom.  Students offer answers to questions posed, but they are the spoken equivalent of fill-in-the-blank questions and a word or phrase is all that is called for in reply.

Anecdote 4.1:

Such answers, are not really talk.  You can tell because no one is listening.  I am sitting in a physics classroom.  Students have been given a worksheet and the same sheet is projected onto the white board at the head of the class.  Diagram one shows a weight on a table attached to a spring.  The spring is compressed.  What do we call this the sheet and the teacher ask?  One student suggests it is momentum; another that it is newtons; yet another that it is kilograms.  No one is trying to figure out why the preceding answers were wrong.  They are calling out technical terms until the right one is spotted by the teacher.  “Potential energy,” says a student, and they move onto the second diagram.

An Anecdote about Ivanhoe:

            My uncle Marty was a great story teller.  One night he told me the story of Ivanhoe and I loved it so that I went to the library to read it for myself.  It was my first book from the adult section of the library and I was a bit trepidatious, not quite sure it would be OK.  I found it and checked it out, no problem.  When I started to read it, however, I was confused.  There was this swine herd, Garth, and he was walking across the English countryside.  No knights in shining armor, no Ivanhoe.  I took the book back, looking for the real Ivanhoe but all I could find was the one by Sir Walter Scott.  So I tried it again.  This time I must have read fifty or sixty pages.  Still all you got was Garth.  I couldn’t figure it out. Then I cam at it a third time, and somewhere around page 75 it all started to happen.  Garth, by the way, becomes Ivanhoe’s squire.  I loved that book, and I always remembered how you had to give an author a good 75 pages to get the story going.  If you didn’t, you might miss the best story ever.

I taught most of my career at the Park School and the students there were comfortable giving me my 75 pages.  I’d start a story and they figured I would bring it around to the topic at hand in time; though it might not be clear just how I was going to do that.  They were comfortable with the idea of trying to figure out where I might be going.  When I started teaching at the Baltimore Freedom Academy, it was clear I was not getting that lengthy grace period.  I only had a couple of pages, as it were.  We talked about it.  I told them the Ivanhoe story, and I talked about the value of listening and playing with the possibilities, and we talked about the difference between teaching where you tell students what they are supposed to know and teaching where you invite them to think about something that is puzzling.  Garth and I did a lot of walking.

Teaching is not just what we have to say.  It’s not about being thoughtful and clear.  If that were so, then textbooks would be far more effective.  The learning we seek thrives on the connection between the material and the open mind of the student.  That connection requires that we listen better…whether we are talking to a partner at a summer gathering or to a group of students.  If we would do that, who knows how much growth would follow.

References:

Furth, Hans. 1966.  Thinking Without Language: Psychological Implications of deafness. New York: Free Press.

Pan, Barbara, Meredith Rowe, Judith Singer, & Catherine Snow, 2005, “Maternal Correlates of Growth in Toddler Vocabulary Production in Low-income Families.” Child Development, 76(4), 763-782.

Herapath’s hypothesis would be revived in the 1840’s sans problem of hardness.  Here for example is Joule writing in 1848:

…since the hypothesis of Herapath, in which it is assumed that the particles of a gas are constantly flying about in every direction with great velocity, the pressure of the gas owing to the impact of the particles against any surface presented to them, is somewhat simple, I shall employ it…

What had only 30 years before been stymied by an impassable metaphysical barrier was now a simple hypothesis.  In this fashion, we find Herapath’s work built upon by such master physicists as Joule, Maxwell, Kelvin, and Clausius.  The kinetic theory had been rescued by the new electro-chemical atom…a complex, whirling, and clanking beast most fit for the new industrial age.

In a text on the kinetic theory, written in 1872, Maxwell pictures atoms colliding.  He begins by observing that the molecules of a gas are not acted upon by any sensible force for the greater part of the time, and so move in straight lines with uniform velocities.  When they move close enough to one another, the molecules act on one another with a force that grows as they approach and then weakens as they move apart.  He then adds: “the free motion of a molecule takes up much more time than that occupied by an encounter.”

And so, Maxwell sets aside the conflict between Herapath and the reasoning of Newton et al.  The bulk of the time a particle is effectively free, and not in collision.  Collisions are mediated by some force, unspecified and unproblematic.  A collision, or an encounter, was simply strong repulsive forces acting as particles approached one another and receded…at least that is all a collision had become.  It had been something very different when the young Herapath had laid out his argument.

Some have looked at this episode as an instance where the customary open-minded objectivity of science had been distorted.  Shadows of elitism or intellectual cowardice, they surmise, had cast a dark shroud over Herapath’s work and prevented it from being evaluated properly.  That is, Herapapth’s rejection was an instance of scientists acting under petty influences and not as good scientists.

But maybe that was not the case.  Maybe we need to open our sense for what was at stake in Herapath’s work.  Let’s look at the actual criticism contemporaries offered and try to see what made his seemingly well-formed work so objectionable.

There were four published replies to Herapath’s work, expressing concern about various aspects…he was too speculative, relied too much on mathematical deductions…but above these objections stood their concern with his portrayal of the molecular world.  He envisioned perfectly hard particles moving freely, slamming into one another and bouncing elastically…without losing momentum or energy.  This was the rub.  Herapath, it turns out, had run smack into a long standing metaphysical controversy.  Perfect hardness logically barred elasticity.

Here’s how Newton had put it in his Principia near the end of the 17^th century:

For bodies which are either absolutely hard or so soft as to be void of elasticity, will not rebound from one another. Impenetrability makes them only stop.  If two equal bodies meet directly in vacuo, they will by the Laws of Motion stop where they meet, and lose all their Motion, and remain in rest, unless they be elastic, and receive new motion from their Spring.

Since it was assumed that atoms as the fundamental particles of matter were perfectly hard…how else could they maintain themselves…they could not bounce off of one another, but would simply ‘splat’ like a snowball against a wall.  Without a source of Spring, without a repulsive force like that of Caloric, Herapath’s vision of the hidden world of atoms and molecules was rooted in contradiction.

Herapath replied to his critics, urging that such metaphysical arguments be set aside.  Grant elastic collisions, grant that somehow momentum is exchanged and no motion is lost.  The proof, he urged, should lie in the proverbial pudding –in the fruitfulness of his analysis.  His strategy works.  The result is elegant mathematically and satisfies the data.  Surely that is enough.

But the critics did not agree.

We do not need to charge Herapath’s colleagues with intellectual cowardice, elitism, or the like.  We need simply to recognize that deep metaphysical notions about the way things must be had led reasonable scientists to deny the premises of Herapath’s work.  Though the molecular world is un-observable, it is clear that Herapath’s views of molecular collisions were un-acceptable and reasonably so.  It was not a case of ‘just the facts’.

As with one Herapath, so with another.  John Herapath, also of the West Country, has left a similarly mixed legacy.  Some of his work was built upon, some not; and little of it was received with enthusiasm by his contemporaries.  What was at work here?  What were the laws of commerce and traffic that determined what would be built upon and what not?

Born near the turn into the 19^th century, Herapath participated in the scientific world of Dalton, Davy, Laplace, and Joule.  He also participated in the booming world of the railroad.  The railway journal he edited was successful; in time it would be named Herapath’s Journal.  As a young man Herapath threw himself into the debate over the nature of heat, and his entry effectively marked a new plateau for the notion that heat was not an ethereal substance, a material stuff, but a certain busy-ness within matter, a mode of motion.  This concept, the kinetic theory of heat, would become one of the core concepts of modern science, one that is still vital, though of course transformed.

Notable scientists before Herapath’s day had offered a notion of heat as a quality of motion, scientists such as Francis Bacon, Robert Boyle, and Daniel Bernoulli.  And in his own day there were those who leaned this way:  Humphrey Davy, president of the Royal Society, Count Rumford, the founder of the Royal Institution, Thomas Young one of the first to propose a wave theory of light, each rejected the caloric theory and sought an alternative in some quality of internal agitation of the particles of matter.

But Herapath went further than they had.  He proposed that the molecular world was a chaos, with particles of a gas, for example, moving freely, in straight lines, colliding with one another.  These collisions, he went on, should be taken to be perfectly elastic, like billiard balls in an ideal world, and he drew upon the mathematical expressions that had been worked out for such collisions.  He then proposed that the temperature of a body reflects the average value of a particular kinematic quality, momentum.  The modern theory links temperature to kinetic energy, not momentum, and there is a difference here, but Herapath was able to derive the general gas laws in a manner closely paralleling modern analyses.  With this as the core of his theory, he went on to consider a host of heat phenomena: specific heats, latent heats, heats of chemical reaction, etc.  Notably, his explanations of diffusion and of adiabatic phenomena, which followed naturally from his principles, addressed major issues then confronting the caloric theory.  His insights and the over-all form of his analysis lay at the foundations of the modern understanding.

This was a most impressive grasp of the truth with a capital “T”.  So much so that we are left with a most curious problem:  How is it that so much right-thinking, so much of what we know to be good science, the facts and perspectives we accept today, how could they have been found false?  For that is what happened.  The scientific community rejected his views.

The leading feature of the little sketch we traced was the puzzle:  is heat a dancer or a dance?  There is a tendency to tell students what they need to know, instead of asking them how they might make sense of things.  In an intriguing book, A is for Ox Barry Sanders talks about the importance of talk: “Young children need to feel lost, confused, and bewildered enough to concoct their own stories in order to climb out of tight situations.  They need to string together narrative threads from here and there to reach meaning in their lives.”

As with the development of children, so too with the development of students.  Telling students what they need to know strikes me as too passive.  Students do not uncover.  That is the work of the text and the teacher.  There is no driving perplexity and so no push to string together a narrative that explains things.

By framing our study with the option, dance or dancer, we move away from telling students the answer.  In effect, the alternative to teaching students the answer is to teach them two answers and to invite them to sort out their strengths and weaknesses, the issues that critically distinguish them.

This respect for the role of problems sets up another clear aspect of our sketch.  The lab investigations were framed by problems rather than protocols.  Instead of carefully laying out what students were to do, I worked to carefully lay out an issue and invited them to figure out how they might resolve it.  I had a colleague once who would regularly stay late working on labs.  I’d stop by to see what he was up to and each time it was clear that he was the one who was really doing the lab.  All his students would do is turn on some apparatus and collect the numbers off the dials.  The effort to make nature answer a question we pose; that is a neat trick.  To go back to dancers and dances, I would ask how they could show whether there had been a change in weight when you added heat? They designed the approach.  And when they systematically would find that the water lost weight, they designed some follow up investigation that would try to control for evaporation.  It was a student, by the way, who suggested comparing equal volumes of hot and cold water.