Thursday, May 20, 2010

Clown Pants

As reported in an earlier post when I taught at the all boys Joliet Catholic I was also a traveling teacher to the sister school, the all girls St. Francis Academy. That was a hassle but the nice thing was that at St. Francis they had a well equipped dark room (FILM!) right behind my lab. I would go very early in the morning and develop film or print pictures. Fun stuff.

On this morning I was mixing up a fresh batch of developer. You have to mix the powder in very hot water to get it to mix. I had about a gallon of the stuff in a large glass beaker and was moving it from one counter to another when it slipped out of my hands. It hit the counter and basically the bottom just fell out of it instantly dispensing 1 gallon of hot developer fluid on my navy blue pants. Yeow! That stings!

And there's the bell for classes to pass. I have 5 minutes. Well, there is nothing that can be done except to get out there and start teaching with my soaking wet pants on. Actually it doesn't show too much because the pants were already dark.

Class begins and I'm teaching away. As time goes on the giggling and laughing are increasing at a fairly steady rate. What's going on? About 30 minutes into the class my pants felt like they were drying nicely. They were but the problem was that when developer fluid dries it leaves behind a white residue. A glance down told me what the hell was so funny. I now had two-tone pants on! white in the front and navy in the back.

Nice.

Tuesday, May 18, 2010

Thumbs Up!

In physics there is this thing in learning electromagnetism called the 'right hand rule'. It works like this: You point your right thumb in the direction of the electric current, your fingers in the direction of the magnetic field and then your palm will point in the direction of the magnetic force on the current. So, given any two you can orient your right hand to find the direction of the third vector. So, I had a number of transparencies (this is WAY before LCD projectors) for practice and it was always quite fun to see the kids go through their contortions to orient there right hands correctly.

On this day though, it was my 4th time through it and it was scalding hot in my room. The lights are low to use the overhead and we're going through the various situations. I can watch the kids pretty well to see if they are orienting there hands correctly. We'd done several and then I spot this girl near the back using her LEFT hand. For crying out loud. . .

LISA! This is the RIGHT HAND RULE. You have to use your RIGHT THUMB for the current!

Lisa looks at me and holds up her right hand and sweetly says, "Mr. Welty, remember? No right thumb."

Wanna get away? Yeah, Lisa doesn't have a right thumb. I knew that but in the heat of the teaching moment I forgot. Oh yeah I wanted to get away. . . big time!

Monday, May 17, 2010

Smoking in School

A Freznel Lens is a very clever little invention. It's a way to make a "fat" lens thin. A fat lens you see will have a short focal lens and sometimes (lighthouses and overhead projectors) that is desired. Unfortunately large fat lenses are very heavy because they are, well, FAT! So what is done is to just copy the shape of the lens at many radii and stick that shape on the flat sheet.



You see these on the underside of the glass plate on overhead projectors and sometimes in back windows of vans and such. I also see them as magnifiers to help people read books with small print. Well, I had one knocking around my lab and for fun I taped it to the window in my room. When you look through it then everything far away is upside down. Just a nice little curiosity and I liked having those things sprinkled about the room.

One day I was lecturing away (fascinating as always I'm sure!) and a student was frantically waving his hand. Bathroom? Not really a good time for a question so I looked away. His hand did not come down and was very insistent.

OK, "What is it?"
"Mr. Welty, the curtains are smoking!"

They were. My windows face east and in the morning I'd close the curtains to keep out the glaring sun. Unfortunately the curtains were 1 focal length away from the lens. Burned a hole right through! Funny. . . unless it had been Saturday!

Tuesday, May 4, 2010

PA Takeover

It's one of the best times of year. We're in May and there is light at the end of the tunnel. I've had a good year with a fun bunch of AP guys (and one poor girl). As I'm walking into the building at my usual early (6 AM) I see one of those AP guys and he shouts (really too loud), "Good Morning Mr. Welty!". Morning. He's down in the basement level of the science wing but I can see him from the stairway. I leave him there and head upstairs and think no more about the slightly off kilter encounter.

About 2 periods into the day the PA comes on. It's loud! It's playing heavy metal. It doesn't stop. UH OH. . .Not only does the morning's encounter come back to me but so does a seemingly innocent set of questions in class from weeks ago. The questions have to do with speakers and multiple speakers being wired in parallel. If someone could get at one speaker wouldn't they be able to drive all the speakers that were wired in parallel with it? Yes of course.

This is what has apparently happened. The buildings and grounds crew are running around looking but really it could be any one of hundreds of speakers. I think I have an idea but I'm smart enough to keep my mouth shut! Interestingly the teachers you'd expect to be mad about this prank are and the ones who you'd expect to think it was rather cool do. No one got hurt and after about an hour the music stopped.

Many of my fellow teachers suggested that this was the work of my AP boys. I assured them that while they were pretty smart that they didn't know a screwdriver from a hacksaw. These seemed to satisfy most and they investigated elsewhere. Of course I knew it was them but I didn't know the details until they arrived at my house at my daughter's graduation party with t-shirts that said, "Radio Free Maine East". Here's how they did it.

They found an empty locker in that basement hallway and put a lock on it. From there they managed to fish the speaker wire from a PA speaker in the ceiling of the hallway. On the morning in question they arrived early and put a CAR BATTERY, amplifier and cassette player into the locker with the output to that one speaker. As expected (taught?) that one speaker gave them access to all the speakers in one entire wing of the building. The school never figured it out. No one was punished and the equipment was removed as stealthily as it arrived.

What a sweet prank. Their 'innocent' questions to me about electricity and circuits months before were all part of the plan.

Saturday, April 24, 2010

Electric Hot Dog (or find the weenie in this story)

Note: This certainly falls into the "Don't try this at home" category so . . .DON"T!

One of my favorite physics demonstrations is electrocuting a hot dog. You take a standard hot dog and shove a big nail into each end. This part is actually kind of hard to watch. Next you attach the dog to a death cord. This was our name for a simple lamp cord with a plug on one end and two alligator clips on the other. Not a really very safe thing to have lying about but we kept it stored away. . . usually. The idea now is to attach the alligator clips to the nails and plug 'er in and thus cook the hot dog. The dog will have several amps running through it and usually cooks in 20-30 seconds. I would bring buns and mustard (NO KETCHUP!) and allow some volunteers to eat the electrically cooked hot dog.

I had built a little stand for supporting the dog while it cooked but on this day I didn't have that stand. I didn't want to just lay the dog on the nasty table. What to do. . .? It's at this moment where I get a great idea and once I get a great idea I tend to run with it and not to consider any possible down sides. My great idea is to cook the hot dog in the bun which I could hold in my hand as surely the bun is an insulator and I can make the bonus point about insulators versus conductors. Brilliant!

So, in front of about 20 sophomore physics students I arrange the hot dog with nails and wires on to the bun. I hold the assembly in my left hand and plug 'er in with my right.

"SHIT!",

says the strangely vibrating teacher while dropping his dog to the floor.

Hot dog buns are NOT insulators. Who knew?

"What happened at school today dear?"
"Not much. Oh, Mr. Welty electrocuted himself and said poop."
"What? "
"Never mind."

Saturday, April 17, 2010

The Drip

Most of the good stories come from my first year of teaching. I was teaching physics and earth science at Joliet Catholic. This was 1975 and Joliet Catholic was all boys. Of course to get full use out of me for the $8300 they were paying me I was also farmed out to their sister school, the all girls St. Francis Academy to which I drove once a day in my own car. Come to think of it here was my schedule. . .

Period 1 - Remedial (or as we called it - Weenie) Earth Science. This was a required freshman course. I had 30 freshman boys (5 rows - 6 seats per row) and 3 sets of identical twins. I also have absolutely zero training in earth science. Needless to say this course turned into Weenie Physics rather quickly.

Period 2 - Regular Physics or Physics for future Convicts. These were ‘regular’ seniors and that means mouth breathing seniors that if they should somehow stay out of prison will be working in their dad’s body shop starting in June.

Now off to St. Francis. . .

Teach physics there. They only have one class. Good kids.

Back to Joliet Catholic - if I didn’t get held up or schedules weren’t screwy I sometimes had time for a brief lunch here.

Now two sections of honors physics which took up the remaining three periods of the day as each class met for a double period 2 days a week while the other class would have a single period that day. But, on Friday I got a special treat. Each class met for a single period so I got my ONE free period of the week. . . Unless I was needed to sub since we all subbed for each other.

Oh, I coached varsity tennis too about which I knew about as much as I knew about earth science but that’s another story.

So, I’m lecturing away at St. Francis one day. I’m sure it was quite fascinating. I see 20 faces locked on me with a concentration (and smiles!) that only the truly inspired learner in the throes of a well crafted lecture can muster. No wandering minds today. I’ve captured them all. This must truly be one of my best lectures ever! I was standing by the windows and not behind a lectern or demo table and I happened to notice a drip of some sort on my shoe. I noticed it because it was clearly fresh and not a dried up little stain. It’s funny about teaching in that your mind is intent on playing teacher and thinking of your subject but there’s other mind that’s thinking “I’m hungry”, or “God I’m still a little hung over”, or “When the hell is this period over”? So other mind thinks, “What’s with that drip”? Moments pass and I see a second drip on my shoe. For sure it was not there before. I keep teaching but also naturally look up for other mind is curious about the source of these drips.

Are my inspired learners giggling? No. Couldn’t be. My eyes return to lock on my students and I actually see a drip fall to the floor out of the corner of my eye! I look up again. Where is this coming from?

Who’s laughing? Actually, who’s nearly peeing their catholic panties? Keep in mind that through all of this I have not missed a beat about Sir Isaac or some other dead scientist. I scratch my head in mild consternation. What’s that? My hand comes back all black. The side of my bearded face is all black!

And drippy!

HOLY Ghost! I’ve a pen behind my ear and the ball has come out. It has been steadily leaking into my beard and then out to my shoe and EVERYONE has known this but me! Now try to get the class back in order. Try acting like this is a normal event that surely all humans have experienced once or twice. Oh sure you young-uns haven’t had the pleasure yet but trust me, you will.

Teaching can be a very lonely affair. I mean you can’t even go to a colleague and say, “Boy I had that leaky pen behind my ear deal today. . . Oh you know!” Nope. You’re all alone out there with a two tone beard and 20 young girls crossing their legs and asking for hall passes to the bathroom.