Notes from the Spring Conference on April 23rd, 2011 are posted with links that are currently available. If you need anything corrected or would like to add anything to a post, please email Bree at Secretary@NCNAAPT.org.
If you were at the conference and would like to print out a certificate for your Professional Development records, you can download it here as a Document or a pdf.
A note from our Program Chair, Paul Robinson, about our meeting:
What a great meeting! About 75 physics teachers–one of our largest turnouts in years–came to hear and see Adam Weiner’s great talk on the Physics of Hollywood Movies only to be followed by Paul Doherty’s behind the scenes tour of the Exploratorium. And the contributed papers were so good that over 30 people stayed until closing time 5 PM to hear them.
We have a new president, David Marasco and VP for Colleges and Universities, Frank , both of Foothill College. Congratulations and thank you! The winners of the Sargent-Welch certificates should email me for the address where they should be mailed for redemption. Thanks everybody for a great meeting.”
“Teaching Strategies for Conceptual Physics for Freshman”
Bree Barnett Dreyfuss and Jon Brix
Amador Valley High School, Pleasanton, CA
Jon and Bree discussed several strategies for teaching freshmen Physics:
Use hands on learning & projects
Use the GUESS (Givens, Unknown, Equation, Substitute and Solve) calculation method
Encourage partner work
Jon and Bree discussed difficulties in teaching the class due to low math skills, special needs students, varying grade levels, etc. The class requires a variety of strategies and resources in order to keep them engaged. Additional resources will be available on Bree’s website.
“Developing Some of the Skills and Values Needed for Success in Introductory Physics”
Jeff Phillips, President of SCAAPT
Loyola Marymount University, Los Angeles, CA
Jeff discussed data that suggests that students that develop their own understanding of concepts through exploration and discussion increases their understanding. Data was collected throughout the college and analyzed to show this improvement; some data was taken from the Lawson Test. Interesting trends include students believing that they are either “smart” or “dumb” and that the method will not change that. Much of the class time has been replaced with teaching metacognitive skills and problem solving skills. Some activities involve the students determining the variables in the problems. For example, students are handed several different objects with different radii, mass, shapes, etc. to determine what affects the moment of inertia.
“The Law of Refraction in the Tenth Century”
Duygu Demirlioglu, Holy Names University, Oakland, CA
Consider a standard problem: given a light ray, incident in some direction on the flat interface between two transparent media, find the direction of the refracted ray. A straightforward and quite trivial application of Snell’s Law yields the solution. Suppose, however, that you are living a thousand years ago. All you have is a ruler—no protractor, no calculator, and no table of sines. A geometric law of refraction—found in the tenth century but largely unknown in the West—will be presented. This approach suffices to solve all the refraction problems (such as critical angle, apparent depth, and lensmaker’s formula) encountered in any physics textbook. It requires hands-on drawing, but no knowledge of trigonometry, or even much geometry; it allows students to understand the physics with very little mathematics.
“Chasing Shadows: NASA’s Kepler Mission”
Edna DeVore, SETI Institute, Mountain View, CA
An updated version of “Transit Tracks” activity where students interpret light curves to determine the period and the size of the transiting planet will be presented.
Paul gave us a brief history of the Exploratorium and its growth over the years. Participants were then split into two groups to explore the Exploratorium’s favorite exhibits. Don and Paul gave tours of the museum and met back together for one big demonstration. Highlights include exploring the reflective properties of the dome at the Palace of Fine Arts and the hidden resonance tube inside one of its pillars. Paul demonstrated the “whirly” sound resonance tube in a larger-than-normal format. A video will be available once its edited.
Adam uses movie clips to teach traditional problems to engage students in the problem. (book available for signing) Some movies are good to show to explore “good science” and data can be collected from the clips in order to create problems. Others are examples of “bad science” and can be used to generate discussions about what is wrong based on the science students know. Adam likes action movies such as Spiderman, Spiderman 2, Spiderman 3, XXX, 2001: Space Odyssey, etc.
Dave Kagan introduced the rules & procedure for Share ‘n Tell including the dreaded gong!
Bree Barnett Dreyfuss – Amador Valley High School
Recently Bree used Energizer AA batteries in a physics lab only to find that several students were being shocked by them. It turns out that the plastic covering on the bottom terminal of the battery was not very well covered and the multi-stranded wire used in the experiment was poking underneath the covering and shorting out the battery. Duracell AA batteries have a better covered bottom terminal. Energizers can be fixed by putting a hole reinforce on the bottom terminal so that the gap is sealed. If you attend her workshop later in the day you can try shocking yourself as her students did.
Tom Rossing – Standford University
Tom demonstrated a noise maker to discuss resonance in open and closed air tubes, self-resonant tuning fork/choir chime made from extruded aluminum.
Jeff Jorgensen – Arroyo High School
Introduced his Case study Portfolio – a how-to about his “case study” activity. Case studies on a variety of topics are available on his website. You can also access his site by going to http://ahs.schoolloop.com and under “Directory,” then “Staff,” choose Jeff to access his webpage. Feel free to email him as well: firstname.lastname@example.org.
Don Rathjen – retired from the Exploratorium Teacher Institute & Foothill High School
Don demonstrated a simple ballistic pendulum (used to measure muzzle velocity) made Teacher Institute-style with a plastic bottle and string. It allows you to measure the muzzle velocity of a toy dart gun. Don’s activity write-up is available here.
Frank Cascarano – Foothill College
Frank shared an angular momentum demo using cordless drill, pvc pipe, drill bit, rotating table. When standing on a rotating platform the drill is run like a helicopter, that makes him rotate in the other direction to conserve angular momentum. Frank’s website is here and his email is FCPhysics@gmail.com.
Dean Baird – Rio Americano High School
You know the Power Balance bracelet? He analyzes the videos and shows that the bracelet does not in fact make you stronger, his YouTube lesson shows the fallacy. He first delved into the phenomenon in his blog entry “Power Balance Bracelet,” and is now working on a full lesson on it.
Dean also demonstrated a jelly baby wave machine using Dots candy rather than buying the expensive demo. Put two dots per side on a bamboo skewer and attach with duct tape. Dean discusses his wave machine in “Connecting the Dots” on his blog, “The Blog of Phyz.”
Clarence Blakken – Gunn High School (retired) and Vernier
Vernier is giving out awards; Clarence wanted to share the new probes from Vernier and his Weblabs available on his website. Also, Great America Physics Days are coming soon! Be sure to check out the Electronic Data Collecting center at the Great America Physics Day.
Tucker Hiatt – Branson/ Wonderfest/ Standford University
Tucker discussed grading strategies including using an error range as we do use in science. For example if they got a 35/45 +/- 3 points may help deal with complaints.
Dan Burns – Las Gatos High School
“A Discovery is an event that reveals your ignorance.” – Dan Burns
A light shown in an LED creates a voltage. A red LED shown into a green LED will not produce a voltage to get it to light. Red LEDs do not have enough energy to give to a green LED (that has a larger band width) but a blue LED can “power” a green LED. A UV LED does not light any color, despite the fact that they have a larger amount of energy. Resource: Center for Nanoscale System Institute for Physics Teachers, reference the “Phantasic Photon” lab for more details.
Veenu Shekhar – Silicon Valley Labs
Veenu helped to manufacture labs about LEDs & solar cells for high school students. Have a grant from the EPA and working on more to produce labs for electronic labs for middle and high school students.
Jeff Arrigotti – PASCO (thank PASCO for the donuts!)
Jeff will be giving away a car track for dynamics and collisions (full set up with springs, etc. and a second one with Physics kit). The car tracks can be attached to several different set ups for multiple experiments.
Gunjan Raizada Chakravarty “Dr. G” – “Sowing the Seed of Physics”
Dr. G has been doing Physics workshops for elementary kids in libraries – gave an example of an inquiry style activity that she does with children. More information is available on her website.
Bernard Cleyet – retired
Explored the conductivity of the hot glue to see if it was the cause of a faulty glue gun (as reported on a PTSOS listserve). Also ask people to respond to a quick questionnaire.
Paul Robinson – San Mateo High School
Lunch is not provided – we will be providing refund for funds collected.
National level (AAPT) update – national meetings need more attendees and possibly reduce number of meetings?
Mentioned his website, www.laserpablo.com and his lab manual is out of print – available online now
By Don Rathjen and Paul Doherty (absent presenter Sebastian Martin) from the Exploratorium
A link to the powerpoint that accompanied this presentation will be linked soon.
“Blinky Lights” is a nickname for a small LED light by Inova called a MicroLight. The light has three settings: bright, dim and blinking. Pressing the light once sets it to bright which is on constantly; two clicks is dim and then three clicks is blinking. The dim setting is actually oscillating on a duty cycle that blinks it back and forth very fast. You can see this by setting it to dim and then waving the light in front of you. The “slow blink” is actually a 3Hz blink rate.
Using a Radio Shaq amplified speaker (~$15), Paul hooked it up to a solar cell and could audibly hear the change in the sound. He analyzed the sound using a free audio analysis software called Audacity and found that the light had 100 cycles/ second. The frequency was actually 97 Hz +/- 3%. Solar cells are attached to a mono mini 1/8” phone jack can be plugged into the speaker or an oscilloscope. The duty cycle is about 10% so that it blinks once every 1/100 hundredth’s of a second, a frequency of 100 Hz. It has recently been discovered that some new ones may be at 200 Hz on dim.
The human eye refreshes in such a way that one bright flash at least one microsecond long will cause the cones to fire for one tenth of a second. The amount of time that the cones continue to flash after depends on the brightness of the light. The memory of a retina is 1/10 of a second but the eye “forgets” 1/8 of a second later.
Blinky Lights can be used to determine the speed of motion of an object if the distance is known. You count dots (100 dots = 1 second). Cameras used have to have a longer exposure time (preferably on a tripod) in order to catch prolonged motion. Cameras can also be on “night setting” on cheaper cameras or even camera phones with the flash off. Either way the exposure time has to be increased; some actions will need only one second while some more artsy photos will need longer. A simple picture like the bike wheel below has a one second exposure time:
Paul demonstrated that the Blinky Lights can be attached to a baseball bat in three places: at the handle, near the head and at the sweet spot. When hung loosely from the handle and struck at the bottom, the baseball bat travels but the blinky light at the sweet spot reveals that the center of mass will travel in a parabolic shape. If struck at the center of mass it will translate to the side with rotation in the other direction. You can find the center of percussion by finding the place that allows the bat to fall straight down without rotation.
Blinky Lights can be attached to a long PVC pipe as well to explore vibration images, resonances, etc. Qualitative observations can be made about several objects without measurements. Blinky Lights can be helpful to show time lapse of specific types of motion.
Blinky Lights are very helpful to show freefall and the acceleration due to gravity by attaching a blinky light to a ball. Two blinky lights on opposite sides can be used to experiment with different pitches.
Don explored how to update role of the old fashioned spark timer using blinky lights. Without measuring time precisely you can say the distance between each pair of dots is a “tic” and use it as a unit of time. By measuring the distance in between you can determine the distance per “tic.” Don showed how by cutting it up you can create a velocity to time graph with each unit of “tic.” This can be adapted with a blinky light on the same moving object. By counting blinks and using a measuring device such as a meter stick within the shot you can create the same type of graph.
Don also modeled how to show acceleration of a two speed shifting toy car as it shifts speed. Blinky Lights can be attached to a variety of cars in order to model different times of motion including constant velocity, acceleration, going over a hill, a “loop-de-loop,” etc.
Paul and Don also shared information about the Teacher Institute at the Exploratorium and several of their electronic sources listed below:
The non-profit Charity foundation portion of NVIDIA is working on bringing visualization into the classroom using their computer components. Video games and simulations have been proven to help students learn visual concepts.
They are asking for people to be a part of the Advisory Committee to help beta-test the visualizations that would be available online. Please contact Toni Hansen if you’re interested.
Toni Hansen, Philanthropy and Social Responsibility
2701 San Tomas Expressway
Santa Clara, CA 95050
CJ Chretien – Leadership Public Schools, Richmond
Chretien showed a few examples of video clips available online in the classroom including the recent Mythbusters episode testing the “Drop vs Shot Bullet” myth. An edited version of the episode is available for download here (removed next Thursday, October 15, 2009).
David Kagan – CSU Chico
After seeing a demonstration about the movement of a soda can that is unshaken compared to a soda can that had been shaken, Kagan wrote an article to “The Physics Teacher.” After that publication, a European TV show contacted him about it in order to use the experiment on the show.
Ann & Jon Hanks – PASCO Scientific
Explained raffle prizes: four PASCO generators for standing wave demo; dynamic set for incline plane (PASTrack). They also demoed a new modular LED strobe that can be realigned for different set-ups.
Don Rathjen – Exploratorium Teacher Institute
Rathjen explained the Science Snack based on the Exploratorium “Vanna” exhibit which is an optical illusion. It is made by taking three copies of a smiling person’s image and using two to create a modified version. It is made by cutting out the eyes and smile of one, apply them upside on one to a second. Starting with the modified and unmodified images upside down, explained that the pictures are of “smiling people.” When rotated though, it is clear one (the modified one) is not smiling. Don uses this exhibit and demonstration to explain the role the brain plays in interpretation of what our eyes see. There is more information available on the Exploratorium’s website.
Bernard Cleyet – retired
Cleyet explored the dissipation of movement of a dynamic cart using several different sensors. Beginning with a cart that had spring oscillators on either side, Cleyet graphed the displacement and found that the decay was not quite exponential. When a force probe is used, the force is fairly linear, as expected with a steel spring that obeys Hooke’s Law. Cleyet repeated the experiment with rubber bands instead of springs and found a much more extreme decay of motion. The rubber band experiment matches a historetic dissipation more than an exponential. The final trial used a magnetic repulsion array for its oscillator. For more information contact: email@example.com
Reklis discussed uses for robotics in a normal physics classroom. His new endeavor is a constant velocity robot with a programmable speed with additional sensors. Currently, it has a sensor that senses an approaching wall and stops. He also plans to have sensors that allow the car to follow a set line on the ground and add a uniform acceleration mode.
Raizada discussed teaching Physics to children at a young age in order to inspire students to get involved and interested in Physics. She is looking for ideas on how to grow her program.
Bree Barnett Dreyfuss – Amador Valley High School
Barnett Dreyfuss discussed “blinky light” activity using small LED lights. The original idea was developed by Sebastian Martin from the Exploratorium to study motion. LED lights with three settings by Inova work well, available typically from Target in the flashlight section for ~$8. The lights are set to the second setting on “dim” which is actually oscillating 100/ second. Samples of images produced by her students are available here. Pictures can be used to show several concepts including:
– projectile motion of objects, including those with unevenly distributed mass whose center of mass will follow a parabolic shape
– centripetal motion when attached to a bike wheel or other rotationary device can show the different speeds that would occur at different radius from the center
– motion of the body by attaching lights to the body and doing simple movements like running or walking
– free fall motion of differently massed or shaped objects from the same height at the same time to experiment with air resistance or to compare horizontally launched projectiles to those dropped
Dan Gill – North Tahoe High School
Gill attempted an experiment in which he would be inside a helium filled balloon to observe the changes in sound. Several theories as to why helium affects the pitch of a person’s voice exist but he doesn’t agree with them. Planning to answer a cell phone while inside the balloon, Gill also inserted a squeaky dog toy, whistle and tuning fork. The idea came from a YouTube video of a street performer using a giant balloon. Before the experiment could be completed, the balloon burst but we are looking forward to potentially seeing it in the Spring. The video of the attempt will be available on the NCNAAPT YouTube site here.
Burns shared an infrared detection card that fluoresces (change color) if exposed to infrared light and can be activated by the infrared light from a remote control. The card is made using materials that can absorb two infrared photons, jumps up an energy level and then down in steps to to release visible light. They are available for around $20, there are cheaper ones that must be activated with exposure to visible light first. Here is a link from Industrial Fiber Optics.
Carl Rosenkilde – Retired
Rosenkilde discussed the sliding bar problem that originally came from another Show & Tell a year ago by Paul Robinson. A bar was placed along the edge of a table so that ¾ of it is off the table. The bar will fall, due to its center of mass being unsupported by the table, and will spin. The length of the bar affects how much rotation will occur (with the same initial height) and Rosenkilde showed us two different lengths, one that rotates to hit the ground at 90˚ and one at 180˚. A solution was presented as to how to prove that angular momentum is conserved. Email: firstname.lastname@example.org
Chuck Hunt – American River College
Hunt made several announcements about the upcoming Spring meeting at the American River College in Sacramento, California during the business portion.
DeVore outline the educational activities available with the Kepler Mission. There are several Kepler Mission Activities, including building an LEGO Orrery, instructions available on website.
There are 374 known planets around other stars. At the Kepler Mission Workshop (details coming soon) all participants get to take home an Orrery kit that can work with a Vernier Optical Sensor to model the Kepler Mission.
A transit is when a planet is observed in front of a star. Teaching transits can reinforce graphing skills and the graphs that students produced will match the published Kepler’s graphs. All graphs, simulations and materials available at Kepler website has all instructional materials
Kepler’s objective is to find habitable Earth size planets orbiting other stars. There are several things that are necessary for life and others that would be helpful. Life on Earth is incredibly diverse and some life exists in conditions that would kill other forms of life, but all forms of life are carbon based and require water. This restricts potential habitable planets to just the right distance from a star, called the “Habitable Zone,” which depends on the temperature of the star. The Transit method of detection is used to find smaller planets. The process for approval and building of Kepler was shared as well as the first images taken by Kepler. Kepler is aimed at the Summer Triangle which is a larger field of view than Hubble. Kepler is an Earth-trailing satellite. The data produced thus far shows a much clearer and refined picture than previously available. The objective of the Kepler Mission is to find out if Earth-sized planets within a habitable zone are common or rare. William Borucki is the scientist behind the Kepler Mission.
This year is the 40th Anniversary of the Apollo program that culminated with landing on the moon. N Cal/Nev AAPT is pleased to commemorate mankind’s greatest adventures with a special appearance of Sy Liebergot.
Sy spoke about what it was like to be a Mission Flight Controller when a monster failure occurred during the Apollo 13 mission and landed squarely in his lap. He related the general details of the explosion as they really happened.
The American Association of Physics Teachers, Northern California/Nevada Section