Michelle Gattuso [Carl Sandberg HS,
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:
Format of Recommendation Letter
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.Michelle, this is very helpful!
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:
"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)."
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!
Larry Alofs [Kenwood Academy, Physics] Handout:
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:
|Color Combination||Resultant Hue|
|red + green||yellow|
|red + blue||magenta|
|green + blue||cyan|
|red + green + blue||white|
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]
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:
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
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
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,
sweeping headlight swept dramatically and somewhat eerily around the
Porter pointed out that this system is a good model for the Advanced
Source [APS] [http://www.aps.anl.gov]
at Argonne National Laboratory, in which the beam of electrons
around and around the ring for hours and hours, and that the
radiation comes out strongly peaked about the instantaneous direction
ultra-relativistic electron beam. To be more realistic, one
should get a blue
laser diode, since the visible component of
increases with decreasing wavelength.
Karlene Joseph [Lane Tech HS, Physics]
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:
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