5 ms·

> People are starting with too many misconceptions and gaps in foundational knowledge. [...] start with at least the basics about the physiology of human visio

> People are starting with too many misconceptions and gaps in foundational knowledge. [...] start with at least the basics about the physiology of human vision A question I ask first-tier physical-sciences graduate students is "A five-year old comes up to you and asks, 'I'm told the Sun is a big hot ball. Awesome! What color is the ball? I really care about the color of balls - I'm 5.' What color is the Sun?". Among the pervasively incorrect answers I get, is a recurrent "It doesn't have a color; it's lots of different colors; it's rainbow color." It reminds me of a failure mode in learning high-school stoichiometry: students not thinking of atoms as real physical objects. And why should letters be conserved?

jacobolus 8y ago
For a 5-year-old I might say something like: “The sun is so bright when it is high in the sky that it will permanently wreck your vision – please don’t look directly at the sun! – so it’s hard to give it a color label, but let’s say it looks ‘white’. Notice that the sky absorbs some of the light coming from the sun to us, changing the apparent color depending on how much sky we are looking through, so when the sun is very close to the horizon and we are looking through a whole lot of sky to see it, it looks orange. In between it looks like various yellows.” Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher.
- mncharity 8y ago
  I'd tweak that as... "The ball is white." So often in education, the most significant bit is neglected. For example, atoms are tiny little balls, sticky little balls that jiggle (insanely fast)... and yet, not thinking of them as real physical objects, something you can teach pre-K, is a failure mode teaching stoichiometry in high-school, and in some intro college chemistry. NASA has done entire museum exhibits about the Sun, bereft of a single ball, or a single true-color image. Imagine a museum exhibit about elephants, without a single model, and only false-color images. Images of elephant surface temperature, of skin parasite density, of average mud thickness, etc. But not a single gray elephant in the room. Would you not then be, "WTF were they thinking?"? I'd skip the distinction between "really is white" vs "appears white because eye has been saturated by brightness, or is monochrome from dimness". And also the issue of color accommodation. Because the Sun really is white. As can be demoed by sunlight through a gap (window, leaves, pinhole camera) on a white surface, or through a neutral filter. I like the emphasis on media. "The white ball... (Not) seen from underground, or from a closet, or from deep in the ocean, appears black. :) Seen from underwater, through tens of meters of water, appears blueish. Seen from under the atmosphere, low in the sky through lots of atmosphere, appears redish. Seen higher in the sky through not much atmosphere, appears white." Years ago I saw a NATO full-sky survey, which had Sun chromaticity as white, even through clouds, until quite low in the sky (in rural Spain I think?, so not much dust or smog). I wish I could be more specific with that "redish" and "atmosphere", but I've not seen real data. If one wants to clearly and correctly explain something to a 5-year old... expect to spend a lot of time with scihub. > Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher. Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. > Talking about color in a precise way with 5-year-olds is even tougher. Here's a fun cautionary tale. There's a genre of science education research ph.d theses that basically goes "We tried to teach science topic X to grade G. <Implict: We didn't really understand the subject, and taught it the-usual badly, often facepalm shockingly badly.> We were surprised and disappointed that this didn't work. We draw the obvious conclusion... Students in grade G are developmentally incapable of understanding topic X." :) I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. Drifting off topic, but a random thought... if you watch even best-practices classroom video, say around estimation, it often seems like the teacher is coaching students on how to pretend to understand the material. Pretend well enough for the teacher to nod and move on. So for instance, the use of an only-locally-equivalent alternative to actually understanding will be encouraged, not debugged. So perhaps there's a mismatch between a nominal goal of "learn science", and an actual goal of "learn to pretend to have learned science". And one might get better results by abandoning one or the other, in favor of consistency and transparency. Random thought. Thanks for the comment!
  - jacobolus 8y ago
    > Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. “Color” is by definition a perceptual response, something that happens inside the brain. It depends on the observer, their eyes’ current level of adaptation, other stimuli which provide context, etc. If you move an object from a light background to a dark background, the color it evokes changes. If you take an object into a dim room and allow the eyes to adapt, the color it evokes changes. Objects don’t inherently have a color. Light sources don’t inherently have a color. Light rays don’t inherently have a color. The same spectral power distribution can evoke (sometimes quite dramatically) different colors in different circumstances. Of course, if you talk to philosophers or physicists instead of color scientists, you might get alternative definitions. > bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones) This is a bit confusing/confused. The retina has two types of detectors, rods and cones. In bright conditions, the rods are overstimulated and so provide no useful signal (and are therefore ignored in favor of the signal from the cones). When the eye is adapted to very dim conditions (e.g. starlight) and looking at a dim stimulus, the cones don’t respond vigorously enough to get much signal from them (and are therefore ignored in favor of the signal from the rods). In some dim-but-not-too-dim situations, signals from both rods and cones are integrated. You can have both light gray and dark gray colors in any kind of context, but which specific stimuli will look light or dark depends on context. * * * > I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. I have a 2.5 year old, and there are many topics which have too many prerequisites to adequately explain to him, or which are not relevant enough to keep his interest. But he is learning a lot every day. Ask me again in a few years what he can learn at age 5. > often seems like the teacher is coaching students on how to pretend to understand the material Trying to teach a classroom with >10 students is extremely difficult in my opinion. I find that lecturing can’t truly teach most ideas; students have to grapple with them independently while working problems or projects or doing their own introspection. A lot of 1:1 attention from an expert mentor/tutor who can suggest problems or projects, ask a lot of questions, provide patient guidance, gently nudge a student back on track, stop the process from time to time and prompt some introspection, etc. is generally the most efficient way to learn. But this doesn’t easily scale to a classroom setting, and 1:1 tutorial isn’t considered economical for widespread adoption. > goal of "learn science" I think to “learn science” students need to be spending at least some time on all stages of the process: coming up with research questions, proposing hypotheses, designing experiments to test them, evaluating the experiments, etc. (And it helps if they have some context for that scientific investigation, e.g. a bunch of experience observing bugs in the forest or trying to make mechanical devices out of meccano or learning to cook or ....) In a similar way, to “learn journalism” students would need to go out and do a whole bunch of interviews and then write stories and publish them. But this kind of learning is hard to achieve in a classroom setting. Of course, “learn how to solve exercises in a typical introductory physics textbook” (or whatever) also has some value, so long as everyone is clear on how it relates to the world.
kyberias 8y ago
It's white, right?
- mncharity 8y ago
  Yes. I've found it an uncommon answer, even with first-tier physical sciences and astronomy graduate students. US cultural convention is yellow, and apparently red in Japan. Lots of orange answers. Astronomy misconception is yellow (the the white point for naming is blueish), plus assorted "and orange"-like noise. Non-astronomy physical science grads are... creative, with misconceptions of light and color a common mode. A nicely disruptive follow-up question is "And what color is sunlight?", setting up a "white" (dominating answer) vs whatever-they-just-said-for-Sun conflict - juxtaposing two rote-memorized bits that they've perhaps not rubbed together before.
  - burfog 8y ago
    If you are standing on the Moon, the Sun is white. If you are standing on planet Earth, the Sun is yellow. As viewed on Earth, sunlight directly from the Sun is also yellow... but normally we include the blue light from the blue sky, which indirectly comes from the Sun. Scattering of blue light by our atmosphere is what makes the sky blue, and by subtraction makes the Sun yellow. This is why normal shadows are a bit blue. They are lit only by the blue sky. Things out in "sunlight" are lit by both the yellow directly from the Sun and by the blue indirect light coming from all directions in the sky. This adds up to being white light.
    - jacobolus 8y ago
      This is also a somewhat confused take. The human visual system adapts to arbitrary light sources within a pretty wide range. Whatever the brightest light source is will typically look “white”. Which is why either an incandescent lamp with 2400K CCT or a fluorescent lamp with 5500K CCT will appear to be “white” after adaptation. The midday sun is so much brighter than everything else in the field of view that to the extent it can be given a color label (again, it will superstimulate all of your cones to the point that “color” loses meaning and permanently damage your vision; please don’t look at the sun) that “white” is really the only reasonable choice. If you pointed a long tube at the sun to keep out light from the rest of the sky and used the sunlight to light a surface that diffusely reflected say 30% of incident light irrespective of wavelength, then that surface would appear white.

jacobolus 8y ago

For a 5-year-old I might say something like: “The sun is so bright when it is high in the sky that it will permanently wreck your vision – please don’t look directly at the sun! – so it’s hard to give it a color label, but let’s say it looks ‘white’. Notice that the sky absorbs some of the light coming from the sun to us, changing the apparent color depending on how much sky we are looking through, so when the sun is very close to the horizon and we are looking through a whole lot of sky to see it, it looks orange. In between it looks like various yellows.” Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher.

mncharity 8y ago
I'd tweak that as... "The ball is white." So often in education, the most significant bit is neglected. For example, atoms are tiny little balls, sticky little balls that jiggle (insanely fast)... and yet, not thinking of them as real physical objects, something you can teach pre-K, is a failure mode teaching stoichiometry in high-school, and in some intro college chemistry. NASA has done entire museum exhibits about the Sun, bereft of a single ball, or a single true-color image. Imagine a museum exhibit about elephants, without a single model, and only false-color images. Images of elephant surface temperature, of skin parasite density, of average mud thickness, etc. But not a single gray elephant in the room. Would you not then be, "WTF were they thinking?"? I'd skip the distinction between "really is white" vs "appears white because eye has been saturated by brightness, or is monochrome from dimness". And also the issue of color accommodation. Because the Sun really is white. As can be demoed by sunlight through a gap (window, leaves, pinhole camera) on a white surface, or through a neutral filter. I like the emphasis on media. "The white ball... (Not) seen from underground, or from a closet, or from deep in the ocean, appears black. :) Seen from underwater, through tens of meters of water, appears blueish. Seen from under the atmosphere, low in the sky through lots of atmosphere, appears redish. Seen higher in the sky through not much atmosphere, appears white." Years ago I saw a NATO full-sky survey, which had Sun chromaticity as white, even through clouds, until quite low in the sky (in rural Spain I think?, so not much dust or smog). I wish I could be more specific with that "redish" and "atmosphere", but I've not seen real data. If one wants to clearly and correctly explain something to a 5-year old... expect to spend a lot of time with scihub. > Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher. Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. > Talking about color in a precise way with 5-year-olds is even tougher. Here's a fun cautionary tale. There's a genre of science education research ph.d theses that basically goes "We tried to teach science topic X to grade G. <Implict: We didn't really understand the subject, and taught it the-usual badly, often facepalm shockingly badly.> We were surprised and disappointed that this didn't work. We draw the obvious conclusion... Students in grade G are developmentally incapable of understanding topic X." :) I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. Drifting off topic, but a random thought... if you watch even best-practices classroom video, say around estimation, it often seems like the teacher is coaching students on how to pretend to understand the material. Pretend well enough for the teacher to nod and move on. So for instance, the use of an only-locally-equivalent alternative to actually understanding will be encouraged, not debugged. So perhaps there's a mismatch between a nominal goal of "learn science", and an actual goal of "learn to pretend to have learned science". And one might get better results by abandoning one or the other, in favor of consistency and transparency. Random thought. Thanks for the comment!
- jacobolus 8y ago
  > Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. “Color” is by definition a perceptual response, something that happens inside the brain. It depends on the observer, their eyes’ current level of adaptation, other stimuli which provide context, etc. If you move an object from a light background to a dark background, the color it evokes changes. If you take an object into a dim room and allow the eyes to adapt, the color it evokes changes. Objects don’t inherently have a color. Light sources don’t inherently have a color. Light rays don’t inherently have a color. The same spectral power distribution can evoke (sometimes quite dramatically) different colors in different circumstances. Of course, if you talk to philosophers or physicists instead of color scientists, you might get alternative definitions. > bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones) This is a bit confusing/confused. The retina has two types of detectors, rods and cones. In bright conditions, the rods are overstimulated and so provide no useful signal (and are therefore ignored in favor of the signal from the cones). When the eye is adapted to very dim conditions (e.g. starlight) and looking at a dim stimulus, the cones don’t respond vigorously enough to get much signal from them (and are therefore ignored in favor of the signal from the rods). In some dim-but-not-too-dim situations, signals from both rods and cones are integrated. You can have both light gray and dark gray colors in any kind of context, but which specific stimuli will look light or dark depends on context. * * * > I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. I have a 2.5 year old, and there are many topics which have too many prerequisites to adequately explain to him, or which are not relevant enough to keep his interest. But he is learning a lot every day. Ask me again in a few years what he can learn at age 5. > often seems like the teacher is coaching students on how to pretend to understand the material Trying to teach a classroom with >10 students is extremely difficult in my opinion. I find that lecturing can’t truly teach most ideas; students have to grapple with them independently while working problems or projects or doing their own introspection. A lot of 1:1 attention from an expert mentor/tutor who can suggest problems or projects, ask a lot of questions, provide patient guidance, gently nudge a student back on track, stop the process from time to time and prompt some introspection, etc. is generally the most efficient way to learn. But this doesn’t easily scale to a classroom setting, and 1:1 tutorial isn’t considered economical for widespread adoption. > goal of "learn science" I think to “learn science” students need to be spending at least some time on all stages of the process: coming up with research questions, proposing hypotheses, designing experiments to test them, evaluating the experiments, etc. (And it helps if they have some context for that scientific investigation, e.g. a bunch of experience observing bugs in the forest or trying to make mechanical devices out of meccano or learning to cook or ....) In a similar way, to “learn journalism” students would need to go out and do a whole bunch of interviews and then write stories and publish them. But this kind of learning is hard to achieve in a classroom setting. Of course, “learn how to solve exercises in a typical introductory physics textbook” (or whatever) also has some value, so long as everyone is clear on how it relates to the world.

kyberias 8y ago

It's white, right?

mncharity 8y ago
Yes. I've found it an uncommon answer, even with first-tier physical sciences and astronomy graduate students. US cultural convention is yellow, and apparently red in Japan. Lots of orange answers. Astronomy misconception is yellow (the the white point for naming is blueish), plus assorted "and orange"-like noise. Non-astronomy physical science grads are... creative, with misconceptions of light and color a common mode. A nicely disruptive follow-up question is "And what color is sunlight?", setting up a "white" (dominating answer) vs whatever-they-just-said-for-Sun conflict - juxtaposing two rote-memorized bits that they've perhaps not rubbed together before.
- burfog 8y ago
  If you are standing on the Moon, the Sun is white. If you are standing on planet Earth, the Sun is yellow. As viewed on Earth, sunlight directly from the Sun is also yellow... but normally we include the blue light from the blue sky, which indirectly comes from the Sun. Scattering of blue light by our atmosphere is what makes the sky blue, and by subtraction makes the Sun yellow. This is why normal shadows are a bit blue. They are lit only by the blue sky. Things out in "sunlight" are lit by both the yellow directly from the Sun and by the blue indirect light coming from all directions in the sky. This adds up to being white light.
  - jacobolus 8y ago
    This is also a somewhat confused take. The human visual system adapts to arbitrary light sources within a pretty wide range. Whatever the brightest light source is will typically look “white”. Which is why either an incandescent lamp with 2400K CCT or a fluorescent lamp with 5500K CCT will appear to be “white” after adaptation. The midday sun is so much brighter than everything else in the field of view that to the extent it can be given a color label (again, it will superstimulate all of your cones to the point that “color” loses meaning and permanently damage your vision; please don’t look at the sun) that “white” is really the only reasonable choice. If you pointed a long tube at the sun to keep out light from the rest of the sky and used the sunlight to light a surface that diffusely reflected say 30% of incident light irrespective of wavelength, then that surface would appear white.