As I mentioned in an earlier post, I was going to try to use more counterintuitive demonstrations to engage students. Ms. Hardy asked that I do one of these demonstrations on the 18th, their last day before the break. In my digging to find experiments of this nature, I discovered the Briggs-Rauscher oscillating reaction (see a video of it here). At this point, the students have seen reactions that cause precipitates to form, states of matter to change, and changes in color. However, once the reaction takes place, they're usually completed in a matter of seconds. The Briggs-Rauscher reaction is impressive, not only because three clear liquids are mixed to make a nice yellow solution, but because the solution then oscillates between yellow and blue for several minutes. It's a somewhat complex reaction (actually two simultaneous, competing reactions), but because it's right before the break, I didn't think explaining the details of the reaction wouldn't really be necessary, since they probably wouldn't have the attention span for something like that right before going on vacation anyhow. I was hoping it would be more like a treat for them to see and ask about when they get back.
Well, that didn't pan out because the necessary chemicals weren't available and Ms. Hardy told me that what they have is pretty much what they're stuck with, since the purchasing budget for the year has already been allocated. Perhaps I could order these chemicals for next semester with TF funds?
In lieu of that demonstration, I'll be doing two others: decomposition of hydrogen peroxide and triboluminescence. Both the chemistry and physical science classes have talked about energy that is consumed or released in reactions, and the physical science class has talked about types of reactions, so both of these demonstrations will have relevance in each class. The decomposition reaction HOOH-->2(H2O)+O2 is catalyzed by catalase, an enzyme found in many living organisms, including humans (it makes the hydrogen peroxide bubble when you put it on a cut) and baking yeast. The baking yeast can be added to consumer strength hydrogen peroxide to produce the decomposition. It produces a nice foam and the presence of O2 can be demonstrated by reigniting a wood splint that has just been blown out. Not only does this give a tangible example of a decomposition, it will also give me a chance to talk about how a catalyst affects the activation energy of a reaction.
Most of you have probably seen triboluminesence before. If you take a wintergreen Lifesaver and crack it with your teeth in the dark, you can see blue sparks. I think this is a neat demonstration of conservation of energy: the mechanical cracking imparts energy upon the electron, which transfers its energy to another atom, which vibrates and releases the energy mostly as UV light. Because wintergreen oil is fluorescent, the UV light causes blue sparks to appear.
I'll be presenting these tomorrow, so we'll see how it goes.
Thursday, December 17, 2009
Sunday, November 29, 2009
Playing catch-up
It's been a while since the last update, but over the past month there have been a lot of days where school has been canceled, half-days where my classes don't meet, or when the students have been taking tests, so there's been less to report on than I would like. However, I did give another presentation a couple weeks ago that seemed to have gone over much better than my first attempt, given the slightly different way I approached the material. This time, in addition to including as many illustrative photos as possible, I also kept myself from delving into long-winded explanations of unnecessary detail and used the presentation, covering different types of mixtures (View it here), to lead into an activity during the second half of the class (See the instructions here). I found it easier to engage the students this time around and found them more willing to offer up ideas for examples of different types of mixtures. I think this was partially because the material was more familiar and accessible, compared to the idea of standards, and also because the students have become more comfortable with me since my last presentation and find participating in my talks to be a nice change of pace.
That said, there are still some students who seem to make it their job to be as disengaged as possible. There is one girl who sits near the front of the room, right in the middle, and the completely flaccid expression on her face and the use of her arm to prop her head up--lest it fall to her desk in boredom--pains me every time. I don't think I could be that unenthusiastic about anything if I tried. That is the breed of student to whom I was trying to tailor my talk, but it seems I have a ways to go still.
One of the persistent problems I've noticed in Ms. Hardy's class is that the students frequently don't bother reading the instructions for things before asking for help. Although I don't mind explaining things if they don't make sense, there are too many students to go around explaining the entire activity or lab to everyone individually. Because of this, you'll notice in the last slide of my presentation the emphasis on reading the instructions before giving up and asking for clarification. However, at the last minute, I found out that there was not enough glassware in the classroom to have each of the substances for the activity measured out for the students in advance. I asked Ms. Hardy during her planning period just before the Physical Science class if there was enough time to change the instructions to indicate that they were to measure out certain substances from a communal container at the center bench and print out new copies, but she said that wouldn't be necessary, that I could just write the modifications on the board and tell the students to refer to them as they worked. It seemed reasonable enough, but as I had predicted, this led to confusion and a lot of people asking, "What beaker of vinegar? There ain't no vinegar. Ms. Hardy, what do we do?" Even many of the students who were participating in the talk seemed to have turned on their selective hearing when I started talking about the modified instructions. I think I was on the right track with trying to streamline the instructions and encourage the students to try everything independently before asking for help, but I have to avoid making any changes after I say something or hand out written instructions.
Anyway, once everyone finally got on the same page with what they were supposed to do, I think the activity was a success. I had the students create a homogeneous mixture, a heterogeneous mixture, and a heterogeneous suspension by mixing sugar and water, oil and vinegar, and water and cornstarch, respectively. I was particularly excited to be able to do this activity, since the water and cornstarch mixture produces a non-Newtonian fluid that many people are probably familiar with, either from playing around with it at home, or from watching people walk on pools of it on programs like Myth Busters. Although there wasn't too much excitement at the water and sugar mixture, the students were endlessly fascinated with this liquid? solid? cornstarch mixture. I think it was a nice demonstration of how something that seems familiar can act in a non-intuitive way. I want to try to incorporate as many of these examples into future activities as possible, since I think a fascination with and a desire to understand those non-intuitive properties is a good way to lead into a pursuit of studies in a scientific field.
Speaking of counterintuitive physical principles, I've recently discovered the fascinating concept of thermoacoustic refrigeration. A friend of mine sent me this article that profiles a new three-in-one refrigerator/oven/electric generator that is powered by a wood fire. Of course, the fire doesn't directly power the other components. They're powered by harnessing the vibrations of the pipe through which the water being heated by the fire passes. The electricity is produced in a pretty straightforward manner, via a linear actuator that acts as a generator, but the refrigeration is the really neat part. A thermoacoustic heat engine is used to induce cooling--essentially, sound is used to keep your food cold. I was blown away by this, since this was a concept with which I had no familiarity. I promptly searched the web for ideas of how to demonstrate this to my students. As luck would have it, a professor at my undergrad university had published a paper on how to build a tabletop demonstration thermoacoustic refrigerator (check it out). It looks pretty simple, so I plan on constructing one of these and presenting it next semester when the physical science class gets to their unit covering waves.
That said, there are still some students who seem to make it their job to be as disengaged as possible. There is one girl who sits near the front of the room, right in the middle, and the completely flaccid expression on her face and the use of her arm to prop her head up--lest it fall to her desk in boredom--pains me every time. I don't think I could be that unenthusiastic about anything if I tried. That is the breed of student to whom I was trying to tailor my talk, but it seems I have a ways to go still.
One of the persistent problems I've noticed in Ms. Hardy's class is that the students frequently don't bother reading the instructions for things before asking for help. Although I don't mind explaining things if they don't make sense, there are too many students to go around explaining the entire activity or lab to everyone individually. Because of this, you'll notice in the last slide of my presentation the emphasis on reading the instructions before giving up and asking for clarification. However, at the last minute, I found out that there was not enough glassware in the classroom to have each of the substances for the activity measured out for the students in advance. I asked Ms. Hardy during her planning period just before the Physical Science class if there was enough time to change the instructions to indicate that they were to measure out certain substances from a communal container at the center bench and print out new copies, but she said that wouldn't be necessary, that I could just write the modifications on the board and tell the students to refer to them as they worked. It seemed reasonable enough, but as I had predicted, this led to confusion and a lot of people asking, "What beaker of vinegar? There ain't no vinegar. Ms. Hardy, what do we do?" Even many of the students who were participating in the talk seemed to have turned on their selective hearing when I started talking about the modified instructions. I think I was on the right track with trying to streamline the instructions and encourage the students to try everything independently before asking for help, but I have to avoid making any changes after I say something or hand out written instructions.
Anyway, once everyone finally got on the same page with what they were supposed to do, I think the activity was a success. I had the students create a homogeneous mixture, a heterogeneous mixture, and a heterogeneous suspension by mixing sugar and water, oil and vinegar, and water and cornstarch, respectively. I was particularly excited to be able to do this activity, since the water and cornstarch mixture produces a non-Newtonian fluid that many people are probably familiar with, either from playing around with it at home, or from watching people walk on pools of it on programs like Myth Busters. Although there wasn't too much excitement at the water and sugar mixture, the students were endlessly fascinated with this liquid? solid? cornstarch mixture. I think it was a nice demonstration of how something that seems familiar can act in a non-intuitive way. I want to try to incorporate as many of these examples into future activities as possible, since I think a fascination with and a desire to understand those non-intuitive properties is a good way to lead into a pursuit of studies in a scientific field.
Speaking of counterintuitive physical principles, I've recently discovered the fascinating concept of thermoacoustic refrigeration. A friend of mine sent me this article that profiles a new three-in-one refrigerator/oven/electric generator that is powered by a wood fire. Of course, the fire doesn't directly power the other components. They're powered by harnessing the vibrations of the pipe through which the water being heated by the fire passes. The electricity is produced in a pretty straightforward manner, via a linear actuator that acts as a generator, but the refrigeration is the really neat part. A thermoacoustic heat engine is used to induce cooling--essentially, sound is used to keep your food cold. I was blown away by this, since this was a concept with which I had no familiarity. I promptly searched the web for ideas of how to demonstrate this to my students. As luck would have it, a professor at my undergrad university had published a paper on how to build a tabletop demonstration thermoacoustic refrigerator (check it out). It looks pretty simple, so I plan on constructing one of these and presenting it next semester when the physical science class gets to their unit covering waves.
Wednesday, October 14, 2009
First Presentation
I've been meaning for a while to post the first presentation I gave, but every time I thought to do so, I was never on the computer on which it was actually stored. Finally though, here is the link: first presentation. I feel that this first attempt was a pretty profound flop. I think I overestimated the students' prior knowledge when I was assembling the material, and underestimated the amount of time needed to present the material, which in turn caused many of the students to lose interest (though that may have already occurred in the first few minutes).
In my mind, I had envisioned talking about the different ways units are standardized, starting with time and length, which are based off of natural constants, an then mass, which is still just a block of metal. I thought the irony of that was kind of amusing, but I think I was the only one in the room who thought so. Part of the problem was that I don't think the idea of basing a unit off of a natural constant--or at least the ones I talked about--made sense. I didn't anticipate most of the class not knowing what an atom was, or at least having a vague concept of what it might be, so the time standard didn't go over so well. I didn't expect that they would know what a light-second was, but I figured that would be fairly easy to explain, though that was assuming they were familiar with the concept that light travels. Again, another flop. Of course, I tried to fill in these gaps during the presentation, but it was hard to quickly explain fundamental concepts like that in a way that allowed the students to immediately understand significance of how they connected to the rest of what I was talking about. Anyway, when I came to my big punchline, "And the mass standard is just a block of metal! Crazy, huh?"--no, I didn't deliver it quite such a cheesy manner--I could hear a chorus of crickets.
In the presentation I included a couple of little cartoons I had drawn containing visual puns, hoping to add some level of entertainment, but I'm not sure if anyone got them.
In the second part of the presentation, I wanted to communicate the importance of keeping attaching proper units to all measurements and to make sure conversions are used where they're needed, so I referenced the famous NASA Mars orbiter fiasco where the orbiter was destroyed because of unit mix-up. A few of the students perked up when they heard about expensive things getting destroyed, though they seemed to be more interested in Mars exploration missions than in unit conversions. That was okay by me though, since at least a few of them were engaging me at this point and asking questions.
On the last slide of the presentation, I included a couple of equations that I was going to use to explain what a Newton is (the unit leading to the NASA failure). By that time though, I realized that given what I perceived to be a lack of interest and/or understanding of the first half of the presentation, I wasn't going to try to explain new concepts right at the very end. If I recall correctly, I gave this presentation the day after I started realizing the very disparate levels of math preparation in the class, so I decided that if simple fractions were difficult for some, introducing the concept of units as fractions wasn't a good idea at this juncture in time.
All in all, I think this first presentation was more of learning experience for me than it was for the students. Hopefully next time, knowing what I know now, those roles will be reversed.
In my mind, I had envisioned talking about the different ways units are standardized, starting with time and length, which are based off of natural constants, an then mass, which is still just a block of metal. I thought the irony of that was kind of amusing, but I think I was the only one in the room who thought so. Part of the problem was that I don't think the idea of basing a unit off of a natural constant--or at least the ones I talked about--made sense. I didn't anticipate most of the class not knowing what an atom was, or at least having a vague concept of what it might be, so the time standard didn't go over so well. I didn't expect that they would know what a light-second was, but I figured that would be fairly easy to explain, though that was assuming they were familiar with the concept that light travels. Again, another flop. Of course, I tried to fill in these gaps during the presentation, but it was hard to quickly explain fundamental concepts like that in a way that allowed the students to immediately understand significance of how they connected to the rest of what I was talking about. Anyway, when I came to my big punchline, "And the mass standard is just a block of metal! Crazy, huh?"--no, I didn't deliver it quite such a cheesy manner--I could hear a chorus of crickets.
In the presentation I included a couple of little cartoons I had drawn containing visual puns, hoping to add some level of entertainment, but I'm not sure if anyone got them.
In the second part of the presentation, I wanted to communicate the importance of keeping attaching proper units to all measurements and to make sure conversions are used where they're needed, so I referenced the famous NASA Mars orbiter fiasco where the orbiter was destroyed because of unit mix-up. A few of the students perked up when they heard about expensive things getting destroyed, though they seemed to be more interested in Mars exploration missions than in unit conversions. That was okay by me though, since at least a few of them were engaging me at this point and asking questions.
On the last slide of the presentation, I included a couple of equations that I was going to use to explain what a Newton is (the unit leading to the NASA failure). By that time though, I realized that given what I perceived to be a lack of interest and/or understanding of the first half of the presentation, I wasn't going to try to explain new concepts right at the very end. If I recall correctly, I gave this presentation the day after I started realizing the very disparate levels of math preparation in the class, so I decided that if simple fractions were difficult for some, introducing the concept of units as fractions wasn't a good idea at this juncture in time.
All in all, I think this first presentation was more of learning experience for me than it was for the students. Hopefully next time, knowing what I know now, those roles will be reversed.
Wednesday, September 30, 2009
What happens when mathematicians die?
They no longer function.
Remember what I said about my impression that the class was moving too slowly and that kids were getting bored? At least some of the students in the 3rd hour physical science class may have finally found a challenge, though not in the sort of material I was hoping it would be. This Tuesday, the class was learning basic unit conversions--really just one conversion, from cm to inches. The task was very straight forward: measure a set of lines on the page in cm, then convert the values to inches using the method and conversion factor explained earlier in class, and presumably, the day before as well.
Some students got it right away and were done in a few minutes, but a couple didn't really follow what they were supposed to do. I explained it again and worked out an example for a few of the students who then understood, but there were a few remaining who, even after one-on-one attention, still had very little idea of what they were supposed to do. I had a hard time trying to figure out what was so complicated about the process, until I concluded that one young man didn't seem to understand how fractions worked. I'm not sure if he was a freshman or a sophomore (there are a few juniors in the class, so he could potentially be even older than I thought), but either way, I'm not sure how one gets that far without understanding such a critical basic mathematical concept. Unfortunately, I had to leave very shortly after making this realization. I plan letting Ms. Hardy know about this if she wasn't already aware, and hopefully I'll have a chance to squeeze some basic math review in where ever I can for him and any other students that might need it.
Remember what I said about my impression that the class was moving too slowly and that kids were getting bored? At least some of the students in the 3rd hour physical science class may have finally found a challenge, though not in the sort of material I was hoping it would be. This Tuesday, the class was learning basic unit conversions--really just one conversion, from cm to inches. The task was very straight forward: measure a set of lines on the page in cm, then convert the values to inches using the method and conversion factor explained earlier in class, and presumably, the day before as well.
Some students got it right away and were done in a few minutes, but a couple didn't really follow what they were supposed to do. I explained it again and worked out an example for a few of the students who then understood, but there were a few remaining who, even after one-on-one attention, still had very little idea of what they were supposed to do. I had a hard time trying to figure out what was so complicated about the process, until I concluded that one young man didn't seem to understand how fractions worked. I'm not sure if he was a freshman or a sophomore (there are a few juniors in the class, so he could potentially be even older than I thought), but either way, I'm not sure how one gets that far without understanding such a critical basic mathematical concept. Unfortunately, I had to leave very shortly after making this realization. I plan letting Ms. Hardy know about this if she wasn't already aware, and hopefully I'll have a chance to squeeze some basic math review in where ever I can for him and any other students that might need it.
Monday, September 28, 2009
First Week
So far, I've been in the classroom on three separate days. I'm almost to the point of knowing all the students' names, though I think a smaller proportion knows mine as of yet. I'm in Miss Hardy's 1st period chemistry class and her 3rd period physical science class. These classes are comprised of mostly juniors and seniors, and freshmen and sophomores, respectively, though--at least from what I've seen so far--the level of complexity of the material being covered so far doesn't differ much between the two. However, being the first two weeks of school, it's a bit early to judge the classes' curricula quite yet, since the beginning of the semester is generally very straight forward.
The first period class tends to be fairly sedate, and at first I thought this was because of their higher maturity level, but I'm beginning to think it has more to do with the early start time. Speaking of which--not to digress to far--I think the 7:20am start is excessively early. When asking Miss Hardy about it, she said that her high school started at 6:50am, though it was a magnet school and she also attended a regular high school later in the day. I think my high school had originally started at 8:30, and there was a bit of a row among students when it was moved up to 8:15am. I recall hearing about studies that had found the optimal time to start high school classes was about 9:00 because of adolescents' tendency to stay up later, and yet require more sleep than the average adult.
The third period physical science class is definitely more awake and ready to socialize during class than their first period peers. I wouldn't characterize the use of cell phones and music players as being excessive, though it's definitely widespread and regard for any existing policy against them is pretty minuscule. I notice, however, that most students don't use these electronic distractions when they're supposed to be doing work, but mostly when they've already finished the task assigned to them. I interpret this as an indication that they need something more challenging and engaging to work on. I don't want this to be interpreted as advocating "busy work" by any means, but when in the classroom, I think being bored is perhaps a worse condition than "not getting it".
The first period class tends to be fairly sedate, and at first I thought this was because of their higher maturity level, but I'm beginning to think it has more to do with the early start time. Speaking of which--not to digress to far--I think the 7:20am start is excessively early. When asking Miss Hardy about it, she said that her high school started at 6:50am, though it was a magnet school and she also attended a regular high school later in the day. I think my high school had originally started at 8:30, and there was a bit of a row among students when it was moved up to 8:15am. I recall hearing about studies that had found the optimal time to start high school classes was about 9:00 because of adolescents' tendency to stay up later, and yet require more sleep than the average adult.
The third period physical science class is definitely more awake and ready to socialize during class than their first period peers. I wouldn't characterize the use of cell phones and music players as being excessive, though it's definitely widespread and regard for any existing policy against them is pretty minuscule. I notice, however, that most students don't use these electronic distractions when they're supposed to be doing work, but mostly when they've already finished the task assigned to them. I interpret this as an indication that they need something more challenging and engaging to work on. I don't want this to be interpreted as advocating "busy work" by any means, but when in the classroom, I think being bored is perhaps a worse condition than "not getting it".
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