Michelle Gattuso [Carl Sandberg HS, Physics]     Taking the WRECK out of Writing Recommendations
Michelle, like the rest of us, is frequently asked by students to write recommendation letters for colleges or for employment.  She passed around (1) summary of information to get from the student before writing such a letter, (2) guidelines on what should appear in these letters, (3) samples of good letters and (4)excerpts from confusing, impersonal and ineffective letters.  Concerning the first point, she recommended that the student provide the following information two weeks before the due date:

• Photocopy of student's completed application form [and SSN, if required!]
• To whom do I send this letter?  By When?
• Institution to which student is applying
  Answer the following questions:
  • The institution is looking for the following information in the letter of recommendation
  • A significant moment that happened in your class that I found most memorable was ...
  • Because ...
  • Additional activities I have been involved with are ...
  • I want to major in ... (or career goals) because ...

• Who is it for?  Will they (the institution) read it, or is it merely a "check-off". Find out what the institution is looking for, and include it.
• What are your experiences with the student in your classroom? Use specific examples (e.g., leader in discussion, time management, why s/he is a good student ...)
• Do not mention the student's race, religion, etc.
• Write honestly and accurately, and be sincere.
• Make the student unique, and try not to write with clichés.
• Avoid guesswork, and include only what you know.  [e.g., do not write about involvement in a sport unless you are a coach].
• Do not write if you are in a bad mood.
• The letter is about the student, and not about the teacher.  It should be in narrative form, supplementing the information the student has already given to the institution.
• Put the letter on the school letterhead, and complete it in a timely fashion.

Format of Recommendation Letter

The letter should consist of these three parts:
• Introduction [Explain how you know the student, what course(s) the student took from you and when, and your general level of enthusiasm for the student] --- no more than 3-4 sentences
• Outline details of student's strengths in your classroom, in terms of communication skills, research papers, curiosity, participation, attitude toward learning; assess academic potential.  Specific categories:   sense of integrity/character, leadership ability, organizational skills, concern for important societal issues, motivation, interest in subject matter, willingness to take appropriate risks, ability to think on her/his feet, consistency of effort and performance, creativity, sense of humor, maturity and personal growth, reaction to setbacks, self-confidence, enthusiasm, special personal characteristics, special academic contributions.
• Conclusion:  This final 1-2 statement should be the actual recommendation.

In closing I will say he was born and raised in a respectful family. So hope since he has made his decision to go on with more schooling he will work hard and make a good student.

Lee Slick  [Morgan Park HS, Physics]      Physics Apparatus - Cheap!
Lee told us that with a very low budget, he made physics apparatus "el cheapo" from inexpensive stuff, but which still showed the physics in the phenomena that he wants his students to learn about:  

• Home-made Thunder/Whistler Tube Lee held up a cylindrical mailing tube about 1 m long and 10 cm diameter with a plastic cap at its bottom end. Dangling down from the cap and attached to its center was a long, flexible spring (about 1 m long and 2 cm diameter). As he shook the tube, a series of eerie, rumbling sounds were produced, reminding us of thunder. Neat! He showed us another, smaller home-made version made from an empty Pringles potato chip can and a spring, and shook it to make more "thunder." Both these versions were just as effective as the commercially available products. Earl Zwicker reminded us that these devices were also useful to show the physical basis of "whistlers." With a colleague holding the Pringles can horizontally, Earl held the free end of the spring with one hand and stretched it out. He then created a transverse wave pulse in the spring by striking it with his other hand in the manner of a karate chop. We heard a sound like a whistle, starting at a high pitch and moving to a lower pitch as the pulse moved along the spring toward the can. After repeating this a couple more times so we could be sure of what we heard, he explained that the spring served as a dispersive medium for propagation of the pulse, giving rise to the whistle sound. This is a good analogy to the "whistlers" produced electromagnetically by ionospheric reflection of radio waves, and which can be detected on short-wave radio. For more details on acoustic whistlers see the website http://www.o-art.org/history/70's/exploratorium/Exploratorium.html, which contains this excerpt:

  "An analog to the echoes of the outdoor rotunda is the echo tube inside The Exploratorium - a 12' diameter pipe extending some 100 feet to the ceiling. Sounds created at its opening are echoed back many times, seemingly more clearly than the original sound. Sharp impulse sounds, such as a hand clap, also produce a high pitch, similar to the stylized rifle sound used in radio and TV Engineer Larry Shaw pointed out that a similar phenomena occurs with electrical impulses in our atmosphere. The sounds, variously called "chirps", whistlers", or "the dawn chorus", can be detected by attaching a coil of wire to an ordinary audio amplifier (or a barbed wire fence, as was done by composer Alvin Lucier)."

• Image Inverter:  Lee passed out a cylindrical film canister, complete with plastic cap, along with a plastic push pin,  to each of us.  We used the push pin to poke one hole in the center of the cap, and then put three holes very close together at the center of the base, to form a triangle.  We then pushed the pin through the lateral surface of the canister, in order to grasp it.  When we looked at a bright region on the wall through the single hole in the cap, we saw the three hole triangle in the base.  However, when we rotated the canister about a vertical axis passing through the center perpendicular to the lateral surface, we observed that the triangle had become inverted.  How come? For additional details see The Human Eye: http://www.mit.edu/~danz/marti/intro.html and The Quaker Oats Canister: The Quaker Oats Canister: http://sdsu-physics.org/assets/PDFs/oatmeal_pinhole_camera.pdf. However, when we rotated the canister about a vertical axis passing through the center perpendicular to the lateral surface, we observed that the triangle had become inverted.  Karlene Joseph remarked that she also used the canister lid as a pin hole camera.  When we moved the push pin across the field of view and on the other side of the hole in the lid, we saw it move in its direction of actual motion.  However, when we moved it in that direction while between our eye and the hole in the lid, it appeared to move in the opposite direction.  Very interesting, Karlene!.
• Tea-bag Rocket: Lee took an ordinary (unflavored) tea-bag, carefully removed the staple holding the string, poured the tea into the waste basket, and set the cylindrical bag upright onto the table to form a hollow cylinder.  He then lit the top of the tea-bag with a match.  The flame encircled the bag and progressively moved down, leaving very little residue.  When very little of the bag was left, it lifted off the table and rose toward the ceiling.  Why?  The tea-bag is almost pure cellulose, and leaves very little residue, unlike ordinary paper. Above the burning bag a convective column of warmer, less dense, air is created, and the last remnant of the bag lifts off the table because its buoyancy  is greater than its weight. Neat,oh! For additional information see Carolina Biological Supply website of Classroom Activities [http://www.carolina.com/how_do_I/classroom_activities.asp], and especially the Tea-bag Rocket:  [http://www.physicscentral.com/experiment/physicsathome/teabagrockets.cfm]

Thanks, Lee --- Physics is Pun!

Fred Schaal [Lane Tech HS, Mathematics]    TI-92 Graphics Calculator Attacks Triangle!
Fred used the TI-92 calculator to illustrate basic geometrical ideas; specifically, general properties of triangles.  First he hooked a calculator to a translucent imaging screen placed on the overhead projector, so that the entire class (we) could see the calculator display.  Then he gave the calculator in question to one of the participants, who used the menu to bring up "geometry", and then "insert triangle".  The participant then clicked on three vertex points in succession, and the triangle appeared.  Fred then showed her how to shift one of the vertices of the triangle by using click and drag. Then she clicked on an icon to construct the altitudes of the triangle, which were seen to intersect at a point, the ortho-center of the triangle. When she moved a vertex, the altitude lines and ortho-center changed continually.  Then she clicked on another icon to obtain perpendicular bisectors of each side, which intersect at a point, the circum-center of  the triangle.  Again, as a vertex was moved, the circum-center also changed.  Interestingly, neither the ortho-center nor the circum-center must always lie inside the triangle. These calculators make geometry fun, Fred!

Web links concerning the TI-92
• Features of the TI-92 Plus:  http://www.ticalc.org/basics/calculators/ti-92plus.html
• Evaluation of TI-92 Graphics Calculator:  http://www.mhhe.com/math/precalc/barnett/ti92.pdf
• The Role of the Calculator: http://education.ti.com/sites/US/downloads/pdf/therole.pdf
• Animating web pages with the TI-92: http://website.lineone.net/~davidbowers/Getty98/main.htm
• EAI (Eric Armin Inc) Education: http://www.eaieducation.com/
• TI-92 Programs:  http://www.ticalc.org/pub/92/basic/cbl/

Larry Alofs [Kenwood Academy, Physics]    Handout: two items
Larry alerted us to the following items: (1) How do optical mice work? [http://www.howstuffworks.com/question631.htm] and (2) Science Guy Bill Nye Killed in Massive Vinegar/Baking-Soda Explosion, from The Onion: [http://www.theonion.com/].  Thanks, Larry!  Earl passed out a copy of the article by Charles M Madigan, Teachers top poll's list of truth-tellers, which appeared in the 08 December (Sunday) Chicago Tribune. 

Bill Shanks [Joliet Central HS, Retired]    Addition of Colors using Spotlights and Colored Cellophane
Bill  brought in 3 rechargeable spotlights with rated luminosities of around 2 million candle power, and covered them with red, green, and  blue colored flexible cellophane sheets -- found in some stores as gift-wrapping -- which he held in place around the edges of the spotlights with sewing hoops.  He was then able to produce high intensity beams of red, green, and  blue  light.  Bill was wearing his Choral Costume -- since he was on his way to an evening concert-- complete with bright red bow tie. The red bow tie shined resplendent in the red light, but looked quite dark in both green and blue lights.  Fish that habituate the 10-100 meter depths of ocean are often colored red in order to be almost invisible in the ocean, which at those depths receives light predominantly in the violet part of the spectrum.  We expected, and mostly got, these combinations:

The patterns of colors on the white boards produced by the (umbra and penumbra) shadows of Bill's hands were very fascinating! Actually, we found that that the red and green cellophane paper were fairly pure, but that the allegedly blue cellophane paper behaved more like blue-green in our studies.

We have seen the lights! A colorful and interesting  visual presentation, Bill!

Don Kanner [Lane Tech HS, Physics]     Questions Concerning the Motion of a Toy Train
Don set up a toy train, consisting of an engine operated with dry cell batteries along with a coal car and two other cars,  which  moved on a circular track about 60 cm in diameter.  He handed out a Surprise Quiz, consisting of these 3 questions:

The toy train on the front table is moving forward with speed v.

1. At any given instant, what part of the train has an instantaneous velocity of 2v in a forward direction?
2. At any given instant, what part of the train has an instantaneous velocity of zero?
3. At any given instant, what part of the train has an instantaneous velocity in a backward direction?

Don attached a paper circle of larger diameter to the end of a large can [say, a coffee can], and rolled it along the front edge of the table with the paper circle sticking over the front of the table.  One could see quite clearly that the point at the bottom of the circle was moving backwards as the can rolled forward without slipping on the table.  Don, we we don't love a surprise quiz, but we do love  The Little Engine That Could ... Make Us Think! Keep the ideas rolling!

Porter put a red diode laser pointer [with the switch held in the "on" position with an alligator clip] on the coal car of the train.  As the train moved around in a circle, the laser produced a "headlight" beam that went in the direction of motion of the train.  When the lights in the room were turned off, the sweeping headlight swept dramatically and somewhat eerily around the room.  Porter pointed out that this system is a good model for the Advanced Photon Source [APS] [http://www.aps.anl.gov] at Argonne National Laboratory, in which the beam of electrons goes around and around the ring for hours and hours, and that the synchrotron radiation comes out strongly peaked about the instantaneous direction of the ultra-relativistic electron beam.  To be more realistic, one should get a blue laser diode, since the visible component of Synchrotron Radiation increases with decreasing wavelength.

Karlene Joseph [Lane Tech HS, Physics]      Synthesizing Planar Motion with x- and y- coordinates
Karlene used three white board sheets (about 40 cm ´ 60 cm) to generate motion in the plane as a superposition of independent motions in the x- and y-directions. The bottom (first) white board was held fixed on the table, the middle (second) white board (lying flat on the first board) was moved along the long direction of the table to represent x, and the top (third) white board (lying flat on the second board) was moved perpendicular to the long direction to represent y-motion. A board marker, which was held at the intersection line of the second and third boards as they moved, traced out the "trajectory" on the bottom board.  If the (middle) second and (top) third boards were moved at constant speed, the marker traced out the trajectory, and produced a straight line in a "slanted" direction on the bottom board.  If the second board (x-motion) was moved with constant speed, while the third board (y-motion) went from fast to slow (deceleration), a downward arc of roughly parabolic shape was obtained.  In addition, if the second board (x-motion) again was moved at constant speed, whereas the third board (y-motion) went from slow to fast, and upward arc of rough parabolic shape was obtained.  Finally, if the second board (x-motion) went with constant speed, but the third board (y-motion) went from fast to slow to "stop", and then from slow to fast in the opposite direction, a full arc of roughly parabolic shape was obtained.  Great!  Having shown the independent motions in the x- and y-directions in an direct, visual, interactive fashion, Karlene then wrote the equations describing the general motions being considered:

• x = v_x0 t
• y = v_y0 t + 1/2 a_y t²
• y = x [ v_y0 / v_x0] + 1/2 a_y [v_y0 / v_x0]²

Walter McDonald  [Hines Veterans MC, CPS Substitute]      Reading X-ray images
Walter showed X-ray images of live organisms that are created by making two exposures at lower and higher energy X-rays, and digitally combined to show separate images for bone and soft tissues.  In general, it is possible to lower the X-ray exposure received by patients in diagnostics, using this technique. These images, obtained through Dual Energy Subtraction Radiography,  [http://www.itnonline.net/ and http://www.gemedicalsystems.com/rad/xr/radio/products/de_perspectives.html] are quite useful in obtaining enhanced images of the skeletal system, as well as images in which the skeletal system is largely eliminated.  He mentioned that these images can also be used to determine bone mineral content, to look for signs of calcium depletion, for example as an indication of osteoporosis. Porter mentioned that one can target the location of a specific element, such as iron in the blood or Calcium in the bones, by using X-rays of energies just below and just above an ionization energy of inner electrons  [ about 13.6 ´ Z² electron Volts for an atom of Atomic Number Z], to obtain images for the distribution of the element in question. With millisecond timing of X-ray pulses, one could make images of the blood distribution in and around the heart, between beats. Thanks for calling our attention to these exciting new diagnostic techniques, Walter!

Monica Seelman, Ben Butler, Sally Hill, Roy Coleman, and Ann Brandon were unable to do their presentations due to lack of time, but will be scheduled for 28 January 2003, our first meeting of the Spring semester.

Notes taken by Porter Johnson