“But Figen, humid air feels oppressive, heavy!” students told me, almost in unison. A very treasured moment indeed. I just got a glimpse of probably a long held misconception: water vapor is heavier than dry air. So, we took out our periodic tables and calculators, and went on to calculate the molecular weight of H2O and how it compares to that of N2 and O2 (most of the atmosphere). Happy that I corrected a major fallacy, I didn’t see the rest coming.
Apparently, there are many other sinister fallacies lurking just underneath the surface of the heavy wet air idea. One student asked “is the formula for water vapor the same as for liquid water?” and was astonished to find out that it is always H2O regardless of phase, even in ice! I said “we like to keep things simple in science” and a couple of ladies giggled “as if!”
Then another admitted that he always thought water split into H2 and O2 upon evaporation which would make wet air heavy. Another student answered him with “No way man. When water vapor condenses to liquid, the molecules get bigger which is why liquid water is heavier than vapor.” So we had a long discussion about molecular dynamics of evaporation and condensation. Also, once I helped the students realize the stark contrast between what they think they know (water vapor is heavy) and something else they know from the Weather Channel (low pressure means rain), the cognitive dissonance (the psychological tension created by conflicting knowledge) drove them to question both “bits of knowledge” and to adjust their ideas. By the end of the hour, they were saying this is SOOO weird, humid air rises. Who knew!
Here are some other common and very tenacious misconceptions:
 Seasons are caused by cyclical changes in Earth’s proximity to the Sun. The main causes underlying this one likely are that [a] intuitively it makes sense and [b] textbooks frequently exaggerate the eccentricity of Earth’s orbit to the extreme that such an idea is logical. The problem is this misconception is extremely popular, from kindergarten to high school physics teachers. A very confused young man once told me openly “Well, my third grade teacher told me that the Earth’s axis is tilted and that is why we get different seasons and it’s winter in the northern hemisphere, when it’s summer in the southern hemisphere. My high school earth science teacher told me during the summer we are closer to the Sun and summers are hot everywhere. Now you are saying my grade school teacher was right all along. And there is all this hype about sunspot activity being the real cause behind global warming. Since the Sun causes our seasons for whatever reason, that sounds believable to me. But you say it’s CO2 in the atmosphere causing global warming. How do I know I can trust you?”
He has a point! And it is very difficult to address the inconsistencies in his education convincingly. I could have told him about my PhD and that I am a climate scientist, but that really doesn’t have much currency in such situations. So I acknowledged that he has a valid point and devoted the next month to demonstrations and data and error margin analysis to empower the students to the point that they could understand the science for themselves. We couldn’t cover coastal geology that semester because we ran out of time, but I think it was worth it anyway.
 The hole in the ozone layer and atmospheric pollution (including but not limited to aerosols) cause global warming. Like the previous one, this one is also very tenacious and difficult to dispel because it is often presented this way in the media and most primary and secondary school teachers share the same fallacy. Perhaps one of the underlying faulty notions here is that the Earth receives heat from the Sun, instead of radiation. So, the thinking here is that the ozone layer shields our planet from the Sun’s harmful rays and its heat. And because there is a hole in the ozone layer, the extra heat seeps in and gets stuck under the ozone layer causing the greenhouse effect. I know, yikes!! I try to dispel this misconception by explaining that though the sun is indeed quite hot, there is all this empty space between the Sun and our planet and heat travels to Earth as infrared radiation from the sun, but the Sun’s output of infrared is only a fraction of its output as visible light. Energy from the sun mostly reaches us as visible light and ultraviolet radiation. (Minor edit to remove confusion with sensible heat and radiation. Sorry about that!).
However, the notion that global warming and ozone depletion are linked is not entirely wrong. As was discussed earlier on RealClimate (Ozone depletion and global warming), original CFC’s as well as ozone itself are powerful greenhouse gases and stratospheric cooling caused by the increase in atmospheric CO2 actually accelerates ozone loss there. Even the replacement gases to be used in lieu of CFCs may have significant greenhouse warming potential. BUT, ozone depletion (“the hole in the ozone layer”) does not cause global warming.
This discussion eventually lends its way to a discussion of aerosols (see Aerosols: the Last Frontier) and although aerosols tend to scatter or absorb incoming solar radiation (hence a warming effect), their net effect is in the direction of cooling because they have a positive influence on the nucleation of clouds which increases our planet’s albedo (ability to reflect light).
 The greenhouse effect and global warming are the same thing. This is another yikes!! Perhaps the root of the problem here is that the discussion of the greenhouse effect in the classroom is often tightly linked with that of global warming. It needs to be explicitly pointed out to students that without the greenhouse effect our planet’s surface would be about 30 degrees C cooler and with wild differences in temperature between night and day. Not exactly habitable. But anthropogenic global warming is caused by the human-induced increase of greenhouse gases in the atmosphere since the Industrial Revolution, particularly CO2. Most of the past changes in climate on glacial-interglacial timescales can be explained by invoking changes in solar activity and greenhouse gas concentrations in the atmosphere, sure. But the warming we have been experiencing in the last few decades cannot be explained if we do not include the effect of greenhouse gases released by human activities (see the IPCC 4th Assessment SPM, and Avery and Singer: Unstoppable Hot Air, just to name a couple).
 Toilets flush in opposite directions in the northern and southern hemispheres. This one is kind of a pedagogically useful misconception because although it is absolutely wrong, the idea behind it is correct and it is primarily a matter of scale. Having said that, I find the Coriolis effect to be one of the most challenging topics for students to grasp as soon as we move beyond its initial descriptive definition. There is often lots of confusion between “to the right” and “to the east” in the northern hemisphere. Plus when we add another dimension to the mix (vertical) in discussing tropical hurricanes, this becomes a serious barrier to understanding. So, I try to avoid any directional terms, like east or west as well as clockwise or counter-clockwise. Not because students are too young to know a non-digital traditional clock, but because from satellite images hurricanes look like they are rotating counter-clockwise. Really can’t argue with what the students are seeing for themselves. But if we keep the terms simple, “moving objects in the northern hemisphere are deflected to the right within the frame of reference of the moving object,” it becomes a little easier to understand, though still challenging. Another challenge here is that the Coriolis effect comes across as a force and it is difficult for students who have not had physics to distinguish between a force and a deflection (an effect).
Perhaps you are now thinking “this may be true in some university in west Michigan but surely in other, more prestigious universities the students know better!” If only this were true. A Private Universe is a video documenting lingering misconceptions among Harvard graduates about the causes behind seasons and lunar phases. The problem is misconceptions are hard to detect because most students are adept at answering questions with exactly what the teacher wants to hear and with correct terminology but without any real understanding of the science. After nine years of collegiate teaching I now know to encourage a casual “say whatever is on your mind” attitude with students. This way, I am hoping to get them to inadvertently voice their misconceptions so I can address them.
And one may be tempted to think this is solely an American problem because the American system of education has been exposed to some serious criticism of late. Again, not so! It’s a global problem. Here are some examples from a couple of quick Google searches. Greek kindergarten teachers harbor deeply rooted confusion about the “ozone hole” and the “greenhouse effect;” while Greek primary school teachers think the ozone hole causes climate change. Australian university students believe a large portion of the ozone hole is over Australia and that the high rate of skin cancer is largely caused by this hole. Junior high school students in Israel seem to understand various processes within the hydrologic cycle, but believe its beginning point is the ocean and the end point is groundwater. And some Turkish in-service physics teachers believe that the moon does not rise and set while Turkish pre-service science teachers think summer is warmer than winter because the Earth is closer to the sun in the summer time.
How about you? Take this quiz to see where you stand ;) Update: Apparently the quiz has been taken off line…
I think, however, there may be some room for improvement in the wording and explanations in this quiz because some questions are very obscure, ambiguous and Chicago-centric. I would like to know what commenters think about it.
Where do misconceptions come from? Personal experiences and intuitive understanding play a large part in fostering misconceptions, and most false notions are reinforced through school and the media. I would like to share with you this delightful and brief story of how personal experiences color the judgment of a bunch of 4th graders about the nature of heat. They have a wise science teacher who broaches the topic with a question: “can you give me an example of something that is hot?” She is expecting answers like the Sun, or a stove or maybe even Britney Spears. But the students say sweaters, hats, and coats. One says “rugs are wicked hot.” The teacher says “when I touch your sweater it doesn’t feel hot.” The students say “Ooh, it’s a matter of time. With time it can be 200 degrees!” Hmmm.. Can you blame them? They spent at least nine years in cold Massachusetts winters and their parents and teachers always told them to put on their warm clothes.
Like this example, some of the problem underlying misconceptions stems from language. “Warm clothes” implies clothes that emit heat, “greenhouse gas” suggests greenhouses are warm because of their gas content, “the rise and set of the sun” suggests the sun is moving across the sky, not the earth is rotating on its axis, and “the theory of relativity” implies all things are relative when actually the theory is based on the constancy of the speed of light.
Let’s go back to our 4th grade class to see how this very experienced teacher addressed the problem. She could just come right out and say “that’s ridiculous, you’re clothes don’t emit heat, they trap the heat your bodies emit.” That would certainly save time to cover more content; instead she decides to do something else (e.g. concept/inquiry based learning for the educators out there). She says “Tomorrow I want everyone to bring something hot from home.” The next day sweaters, scarves, hats and even a down sleeping bag arrive. The teacher puts a thermometer into each one and they wait until the next day for them to get hot on the inside. The students are convinced the down sleeping bag will be 400 degrees! They rush in the next morning and quickly check their thermometers. 68 degrees! They’re shocked. But convinced? Not a chance! They are not going to dismiss 9 years of personal experience just like that. “Cold air got in there!” says one little girl. “When I sit in the car with the windows up, it gets hot. We need to hide our clothes.” So sweaters and hats get put into drawers and closets with their thermometers snuggly in them. Another night goes by. The next day they rush in and check their thermometers again. Again 68 degrees! Except one student has 69 degrees. They all applaud. Still not convinced, after all there has been indication in the right direction! Several nights go by like this. Finally serious doubt begins to ensue. So the teacher says “I want everyone who believes clothes are hot to walk to this corner” and she points left; “and the ones who think clothes trap the heat our bodies emit to this corner” and she points right. Most of the students go to the right but three stubborn ones go to the left. Guess you will always have the denialists! But no matter what, these students experienced two things more important than heat: the scientific method in action and sometimes the way something feels is only that and not reality.
So, are misconceptions barriers to understanding or helpful pedagogical tools? That will largely depend on the individual teacher’s (professor’s) style and interests. But the important thing is to  challenge misconceptions,  demonstrate their faultiness through carefully devised experiments (ideally by the students),  help develop multiple working hypotheses to understand the meaning of the results of these experiments,  devise more experiments to test and retest each hypothesis, and  NEVER let a student leave the classroom with a diagnosed misconception uncorrected. And, perhaps the most effective method for eradicating misconceptions at every level is going to be investing large quantities of time, money and effort into educating primary and secondary school educators. NSF has many programs that fund such efforts, but much more effort is clearly needed on a global scale.
Disclaimer: I am not an educational psychologist. I am simply a college professor and ocean/climate scientist enjoying a rich and intense teaching career in the Geology Department at GVSU. Also, my anecdotes and all my quotations are intentionally fictionalized to protect the confidentiality of students. The ideas expressed in the quotes are amalgamations of multiple repeated ideas expressed to me from students, professors and colleagues alike since I started graduate school in 1991 at Middle East Technical University in Ankara, Turkey; and the misconceptions I mention are not unique to any of my students but are listed in over 7000 published misconceptions about science.