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.
Thursday, May 20, 2010
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!
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!
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.
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.
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