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Opinions on elementary school science homework

  1. Oct 26, 2017 #1
    Hi all. I'm reviewing my daughter's science homework and I disagree with how things are being presented. I wanted some feedback from everyone here to get a sanity check on my own thinking. The exercise is this: answer whether these properties of matter are either an observable property or a measurable property: shape, texture, odor, length, state, sink/float, weight, temperature, magnetic, volume, density, mass.

    1. I have a problem with the "or". If we cannot observe a property, how could we ever measure it? The act of measuring requires observation. I can observe whether something's solid, but I can also measure it according to different criteria (e.g., the rate of molecular translation, etc.); I can observe something's texture, but I can also measure it (usually via lasers these days); etc.

    2. sink/float: these are actions: verbs, not nouns or adjectives. How can these be properties? Density is a property, but sink/float depends on the density compared to that of the fluid it's in (among other things). It's like asking if sit/run or ascend/descend are observable properties or measurable properties. They are actions to be observed or measured, but not properties of the matter itself.

    3. weight: weight is a force, not a property of matter. That is, changing the curvature of spacetime in which a mass resides changes its weight accordingly without any change to the mass itself (although the consequence of the modified force might change the mass). No?

    4. more generally, isn't any observable property also measurable? If we can observe it, we can visually measure it, even if this form of measurement is highly imprecise. It seems to me "observable" and "measurable" are not mutually exclusive.


    This seems like a poor exercise to teach scientific concepts: am I crazy and/or ignorant (NOT mutually exclusive)? Thanks for any opinions.
     
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  3. Oct 26, 2017 #2

    phinds

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    I completely agree w/ you.
     
  4. Oct 26, 2017 #3

    TSny

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    This is likely to generate some interesting discussion. The question is open to interpretation. We don't know how the teacher talked about "observable" and "measurable".

    It does seem that there are properties that would be both observable and measurable. As a guess, it could be that "measurable" is meant to denote a property that is quantifiable so that you can assign a numerical value and a unit. There might be properties that are observable but not measurable in that sense. For example, "taste".

    There might also be properties that are measurable but not observable, depending of course on the definition of "observable". For example, the wavelength of a certain color of light is measurable. But one might say that the wavelength is not observable. To measure the wavelength, you could pass the light through a prism and observe where the light strikes a screen. You measure things like the distance from the prism to the screen and then deduce with calculation what the wavelength must be. But you are not really observing the wavelength itself.
     
  5. Oct 26, 2017 #4

    kuruman

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    Let's talk about motion that is not one of the items on the teacher's list. Is motion observable? Absolutely yes. You can tell if something is moving just by looking at it. Is motion measurable? I am not sure. I can measure the object's speed and acceleration and predict where it will be in the future, but have I measured motion? I would say no. What about odor? I think that is an observable, I can tell if something smells nice of if it stinks. Furthermore, something that is stinky to me may smell OK to someone else. Sure we can measure the percentages of chemicals that make up an odor, but if we do, have we observed odor? What is the best way to decide whether something is stinky, look at a list of chemicals (measure it) or just smell it (observe it)? Perhaps the teacher wants to make a distinction between items that can be quantified with a single measurement (mass, length, temperature ...) that are informative and items that can be quantified by a number of measurements (shape, texture, odor ...) that are not very informative about the nature of the item.

    I am not sure that this is such a poor exercise to teach scientific principles. There are lot of people out there with fuzzy thinking. The teacher's next step may be to say to the class, "OK, we are doing science here and we need to be precise about how to think of the world. Items such as odor, texture and shape have a place in the English language to describe properties of objects, but they are not important in a science class where the goal is to measure properties of objects and see how they fit in our understanding of the world."

    Your obvious course of action is to talk to your daughter's teacher and see where he/she/ze is going with this.
     
  6. Oct 26, 2017 #5
    Thanks for the feedback. I definitely agree it's open to interpretation, although I really don't see how "sink/float" could be considered a physical property. Googling around I do see weight often listed as a physical property, but that still seems like a force to me, not a property of matter.

    If "measurable" does mean something quantifiable with a number and unit of measurement, wouldn't everything be measurable? To take "taste" as an example, we could define a system of measurement to denote saltiness, bitterness, sweetness, etc., and thereby measure how something tastes, couldn't we? Such as taste = pH * scoville heat unit (etc).

    If "observable" means whatever can be seen with the naked eye, then length, mass, light, etc., are both observable and not observable, which would seem to render the term meaningless. I can see certain lengths with my naked eye, but not tiny or monstrous lengths; I can see mass within a certain range but not outside that range; as you point out above we can all view certain types of light but not others (unless you're blind or wear eyeglasses or are color blind, etc.). It seems such as vague term as to lose meaning for me. Schroedinger's Observability Coefficient: the magnitude to which an observable property of matter can be both observable and not observable. :)

    Just trying to learn along with my daugher, so thanks for the help. :)
     
  7. Oct 26, 2017 #6

    phinds

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    Although I agree w/ you, keep in mind that that might be considered a bit too advanced for elementary school. Not sure. Just sayin'
     
  8. Oct 26, 2017 #7
    Hmmm, I dunno. I've seen objects in space that I'm told are moving, but I would never know that even though I'm staring intently at them. I would need some frame of reference to compare the object to to know it's actually moving. That is, measure its distance compared to something else over time, even if my eyeball measurements aren't very precise.

    Yes, I'm asking very nicely for some clarification from the teacher. This homework was given today and is due tomorrow and is already complete, I was just curious what others thought.
     
  9. Oct 26, 2017 #8

    Bystander

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    Keep us posted on this please.
     
  10. Oct 26, 2017 #9
    Good point. I try very hard not to confuse my daughter with concepts that aren't appropriate for her age level.
     
  11. Oct 26, 2017 #10

    kuruman

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    Sure, you look up at these objects and you observe that they are not moving. The fact that you were mistaken does not mean that motion is not observable.
     
  12. Oct 27, 2017 #11

    haruspex

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    Some of the attributes we experience directly (shape, texture, taste, odour, weight) while others we only infer from observation of other attributes (magnetism, density). Mass I would put in the first group.
    I think this accords with TSny's comment.
    Several in the list are properties of objects (extrinsic) rather than the material of which they are made (intrinsic), so I agree it would be better to call these properties of objects rather than properties of matter.
    At one level, yes, if you can observe it then you can invent a measure for it, even though the measurement may be partly subjective, such as shape.
    I hope the teacher does not intend to get into qualia: is your experience of redness the same as mine?
     
  13. Oct 27, 2017 #12
    I'm not a fan of the oversimplifications often made in elementary school science. But change and improvement is likely an uphill battle since in most cases those creating elementary science curricula view being an expert in elementary education as 10 times more important than being a subject matter expert. They often have convinced themselves that the oversimplifications and inaccurate descriptions are necessary for learning at those ages and they shift the burden to later science courses to provide greater accuracy.

    My first step would be to determine if the inaccuracies at hand originate with the textbook or with the teacher. If the book gets it right, at least you can point to the textbook for the proper descriptions. But if the book gets it wrong, you have an uphill battle providing clarification beyond your own daughter.
     
  14. Oct 27, 2017 #13

    ZapperZ

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    I'm usually a stickler for accuracy and proper terminology. But I have to disagree with most folks here on this one.

    We need to put things in context here. This is for an elementary science class, and the teacher is using "ordinary" language to ask the students these questions. Therefore, the word "observable" in everyday language means "can be seen with your own eyes", while "measurable" means that "you might not see it easily with your eyes, but you can measure some quantity associated with it".

    From what I can "see", the aim here is for the students to realize that there are things about our world that we can directly see with our eyes, but there are also other properties in which we cannot obtain as directly, and can only be obtained via some measurement. We really cannot expect students at that level and that age to be able to use our accurate, scientific language for this exercise. They'll be tied up on trying to understand the language and the whole intention of the exercise will be lost.

    Zz.
     
  15. Oct 27, 2017 #14

    symbolipoint

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    SciFi, this is just my impulsive reaction from seeing only your first two paragraphs:
    Kids in just elementary school are not ready for critically studying sciences or "science". You, an adult and much more developed, can more capably be critical. The kids are generally not ready. Someone is assigned the work of trying to prepare the kids. Help yours the best that you can but do not be mean to them nor to their teacher.
     
  16. Oct 27, 2017 #15

    symbolipoint

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    SciFi, you reported this:
    I would hate to tell you about something similar that I complained about for getting into trouble myself in the future. When I spoke up years ago, colleagues told me I was too critical and expecting too much.
     
  17. Oct 27, 2017 #16

    symbolipoint

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    Take this idea: Science education gets better in and after high school.
     
  18. Oct 27, 2017 #17
    I would prefer to describe things as qualitative and quantitative rather than observable and measurable. Integrating math as much as possible (through quantitative measurements) in elementary science 1) provides additional opportunities to practice and see the usefulness of math and numbers 2) prepares students better for middle school science when they will encounter formulas and quantitative predictions and 3) better prepares students for the physical sciences that are dominated by quantitative thinking.

    I've worked with enough elementary school students to know that most will grasp the distinction between observations to which a number can be assigned (through measurement) and observations which are more difficult to assign a number in a meaningful way long before they reach the 6th grade. Of course, the discussion in K and 1 is much different from 5th and 6th grades. Still the ideas of whether or not a number can be assigned to an observable is key to both math and science as soon as the necessary math foundation is in place.
     
  19. Oct 27, 2017 #18

    ZapperZ

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    But now you're talking about different things. The original question isn't a matter of PREFERENCE. We all have different ways of doing things and thus, different preferences in these things. Rather, the OP had strong opinions that these things are wrong!

    I argue that based on the level of understanding and what the INTENT of the exercise was, I do not see it being wrong. That is my preference.

    Zz.
     
  20. Oct 27, 2017 #19
    For me, the degree of wrongness depends on the specific grade - such an inaccurate oversimplification is a lot more wrong for 6th graders than for 1st graders. But since the OP did not give a specific grade, I decided to speak in terms of better and worse approaches (shades of gray) rather than the black and white of right and wrong.

    But all teachers would do well to consider whether their approach is going to help or hinder learning downstream. Making the error (and it IS an error) for 1st graders is much more correctable before they hit middle school than making the error for 6th graders.
     
  21. Oct 27, 2017 #20

    ZapperZ

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    No, I do not see the CLEAR error here. Let's re-read the original question:

    That is the original question. The REST of the first post were based on the OP's interpretation of what he/she thinks is the problem with the question.

    So how exactly can you pick out the error in that question? You have to first anticipate at what the correct answers should be from the teacher, and then show why, beyond just a matter of semantics and interpretation, that the answers are outright wrong.

    Zz.
     
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