I can't see these presentations you're putting together, but just judging from your SB writing, I would imagine they're superb.
Doumo arigatou gozaimasu. :biggrin:
So, we're sitting there after the presentations last night, just two divemaster candidates and a pair of instructors, when one of the instructors says that the next thing they usually do in training (once the trainees are in the state that we find ourselves) is that they spring a topic on the trainees, give the trainees a few minutes to prepare, and then have presentations right then and there. We, on the other hand, were planning to head to the pool for some wet work. Of course, since the pool was unavailable (there's a meet this weekend at LSU, so the Nat is full of practice and prelims), well... But I get ahead of myself.
The main thing on the schedule for last night's class (other than the pool) was a presentation each by the two of us. My compatriot was to do a presentation on "pressure", and mine was to be on "buoyancy" (as mentioned previously). As I'd done the first presentation of our first round, it was his turn to lead off, which he did with a *bang*, quite literally. (He had a balloon over the valve on a tank. As he introduced himself, he opened the valve. Everyone braced, and *POW*, it quite expectedly popped.
) Anyway, his presentation was quite nice, indeed.
And then it was my turn.
After introducing myself and the presentation, I led off with a pitcher of water, into which I dropped a floating stress-ball heart and a sinking rubber ball. Then it was on with the show. Everyone seemed to enjoy the cartoonish art sprinkled here and there, and the Monty Python joke ("very small rocks") got a chuckle. Shortly thereafter, I arrived at the "What determines buoyancy?" section.
Although the pitcher of water was a nice little attention grab at the beginning of the presentation, its inclusion there was almost but a ruse. Now the real purpose presented. I removed the heart and ball and tossed them aside, and out came those stalwarts of physics teachers everywhere, a can of Coke and a can of Diet Coke. In dropped the can of Coke, which promptly...
...um...
...refused to sink. Some combination of the water at the shop and carrying the can from home apparently added together to make the can right on the positive borderline of neutrally buoyant. I had never had that demo fail before... *ever*... but next time I'll stash the can in the fridge at the dive shop the day before, and I'll bring my own water from home. (The can sank perfectly normally once I got home. Go figure.)
Anyway, so they saw the can *just about* sink. Then in went the can of
Diet Coke. It had no problem floating, of course, and it graciously demonstrated that it was significantly *more* positively buoyant than the rebellious Coke. What was the difference? Well, the can of Coke weighed 13-5/8 ounces, while the can of Diet Coke weighed 13-1/8 ounces. So, obviously, *weight* determines buoyancy.
Ah, but wait (pardon the pun)! Out came a small glass jar (filled with unnamed something) that *also* weighed precisely 13-1/8 ounces. Well, if the Diet Coke floats and the jar weighs the same, will it float? Into the pitcher it goes, and (unlike the rebellious can of Coke), it drops right to the bottom. Why (considering it weighs the same)? The jar is much smaller than the can (and the pen mightier than the sword, of course), so it displaces less water, which means (thanks to Archimedes and his bathtub two slides back) it's buoyed up by less force. So, *volume* is also involved in determining buoyancy.
What do you you have when you have weight and volume showing up at the party? ("Any science people in here?") Why, *density* of course. (Run the density procession from styrofoam through lead, and reference the rubber ball from the intro, just to tie it together.)
From there, it was just neutral buoyancy, why you want to maintain it, and what you have to compensate for (using, amazingly enough, a
buoyancy compensator -- sorry, PADI, we don't throw "device" in all our names
). But wait, we can't forget about freshwater versus saltwater, can we?
And so, out comes the final piece of the physics demonstration set. Back into the pitcher went the rebellious can of Coke (which still didn't *quite* sink, but it was just about neutral), and out came a bottle of nondescript clear liquid. Yep, concentrated salt water.
With just a bit of flair, the salt solution is poured into the water-and-can-bearing pitcher, turning our nice not-quite-spring water into salty not-quite-ocean water. Even a rebellious beverage must eventually yield to the awesome power of simple physics, and so, the can popped right up to the surface and *really* got to floating, showing in plain sight the effect of the density change (freshwater versus saltwater) on buoyancy.
Toss in a quick page about buoyancy checks in the pool (just to give a heads up and, perhaps, to end up with at least a couple people who will know what we're doing when we get to that in the pool, hehe), and it was time for the wrap, a quick on-screen quiz, and ending the lesson with Archimedes' bathtub on the screen (now with about six rubber duckies in it).
This time I had a much better idea about what procedural pieces were *required*, and it was quite easy to be sure those were hit. (When you've got a slide allocated to each procedural requirement, it's rather hard to miss any, eh? :biggrin
The bits of art got kudos, as did the humor. (They like my style, as they agree that a little sprinkling of relevant humor does wonders for holding attention.) What really impressed was the basic physics demo. Neither instructor had seen that one before (what, did they never attend a science fair?
), and such a simple demonstration of the concepts is just what you need to give students something with which to connect. (One of the instructors said he just *knew* the bottle was saltwater, but he didn't know exactly what of it until he saw the demo.)
Anyway, both instructors said they had a hard time coming up with any constructive criticism for the presentation. One said it was hard to criticize too harshly when you're watching the presentation and thinking, "We need to take that and put it in *our* classes."
I came in one point from the top of the scale, and they said it was probably about that and a half, but since there are no half points... (Personally, I noted a few places I can improve, but I didn't make it a point to note every detail out loud.
) Regardless, it certainly improves your confidence when you nail a presentation.
Of course, it also improves your competence when you get blindsided...
So, we're sitting there after the presentations last night, just two divemaster candidates and a pair of instructors, when one of the instructors says that the next thing they usually do in training (once the trainees are in the state that we find ourselves) that they spring a topic on the trainees, give the trainees a few minutes to prepare, and then have presentations right then and there. We, on the other hand, were planning to head to the pool for some wet work. Of course, since the pool was unavailable (there's a meet this weekend at LSU, so the Nat is full of practice and prelims), well... ...without anything else to do (hehe), we plunged right in.
If you knew me well, you'd know that I've got the OC part of OCD down in spades. I'm not obsessive or compulsive to the point of it being a disorder, but (for example) I can't watch
Monk without being frustrated that "they're doing it wrong!" (Ask me on a SI sometime and I can give you a few highlights.) Anyway, doing a spur-of-the-moment presentation without time to make any training aids or other interesting bits is not my forte, but at the same time, I'm not going to shy away from it. (As a sound guy and as an occasional wedding photographer, I'm not at all averse to stressful situations, and I have enough of a drama background to enjoy the thrill of "stagefright".)
Obviously, I didn't do as well on the cold-turkey seat-of-the-pants presentation, but I didn't fail miserably or anything. It was, perhaps, more of a learning experience than the main presentation (which was more of practical experience than brute learning). I was definitely far more nervous. If anything, it gave me a great incentive to study *everything* in order to be ready for *anything*. As a sound guy, I know every button, every knob, every pathway in the sound board so that if anything happens, I can respond well (even for those things that you'd never have imagined and could not have practiced). To be the instructor I plan someday to become, I'll have to be just as familiar and have just as broad and as thorough an understanding of the diving material.
Well, anyway, needless to say, it was another great night. :biggrin:
