September/October 2017 – Vol. 30 No. 1

The Teaching Length Scale

Posted: Tuesday, May 6th, 2014

by Galen T. Pickett

Physics can be organized by the size and duration of events. When we teach Newton’s mechanics, the examples we use typically are on length scales of meters and on time scales of seconds (tossing a ball, sliding into second base) and run up to solar system scales (tens of millions of kilometers for an Astronomical Unit, and tens of millions of seconds for a year). But, unless your classroom is equipped with technology at the extreme ends of the sophistication scale (chalkboards at the primitive end, and SmartBoards at the super-fancy end), you probably use ordinary whiteboards and erasable marker to make sketches and calculations for your students. The marks you make on this surface meet some basic criteria: they have to be wide enough (half a centimeter or so) to be clearly seen from every vantage in your room and they have to strongly absorb visible light – making a visibly saturated mark. The width of the marks is controlled by the properties of the pen tip, and the saturation of the marks is controlled by the pigment in the marker, but there is another, often overlooked length scale in your markings.



What is the thickness of the marks? It can’t be zero, and it can’t be on the order of millimeters (you can easily feel roughness on the scale of tenths of millimeters with your fingertips, the width of a single human hair). What I have below can be organized into a demonstration or a full experiment supporting topics in waves and optics.

  • Have a supply of “wet” whiteboard markers on hand. A couple of different colors if you are doing a demonstration, enough for each group to have one if this is a class-wide exploration.
  • Make several marks (or have your kids make marks on their whiteboard slabs), different orientations, curly-cues, some nice cursive if you can manage it, ask for what length scales your students observe.
  • Ask about the thickness of the marks … how far from the surface of the whiteboard do they jut?
  • Use a web-camera and a second light source to show what the marks look like up-close. Make sure you can see the marks “through” the reflection of your light source.
  • If you see other colors … and you will … ask your students if that reminds them of anything. Rainbows, and soap-bubbles, oily sheen are what comes to my mind.
  • What happens when marks “cross” each other? If you press hard when writing, where do you expect the marks to be thinnest?

Figure 1

Here is what is happening. The “green” and “yellow” rays add up “constructively.” (See Figure 1.) That is, they are in constructive interference so you see this wavelength strongly reflected, even if this color were not present in the pigments of the oily marker layer.

The presence of this “rainbow” (see Figures 2 and 3) indicates that there is some interference going on, so the thickness of the marker layer has to be comparable to the wavelength of visible light.

Green light is in the neighborhood of 500 nanometers in wavelength, or 0.5 micrometer. A human red blood cell is approximately a disk of thickness 5 micron, and radius 15 micron, so the marks you use to teach physics are a factor of ten smaller than that cellular scale. When you teach physics, astrophysics, mathematics, history and poetry, you are using one of the great sub-micron teaching technologies of the twentieth century.

Dr. Galen T. Pickett is with the Department of Physics and Astronomy at CSU Long Beach and a member of CSTA.

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State Schools Chief Tom Torlakson Announces 2017 Finalists for Presidential Awards for Excellence in Mathematics and Science Teaching

Posted: Wednesday, September 20th, 2017

SACRAMENTO—State Superintendent of Public Instruction Tom Torlakson today nominated eight exceptional secondary mathematics and science teachers as California finalists for the 2017 Presidential Awards for Excellence in Mathematics and Science Teaching (PAEMST).

“These teachers are dedicated and accomplished individuals whose innovative teaching styles prepare our students for 21st century careers and college and develop them into the designers and inventors of the future,” Torlakson said. “They rank among the finest in their profession and also serve as wonderful mentors and role models.”

The California Department of Education (CDE) partners annually with the California Science Teachers Association and the California Mathematics Council to recruit and select nominees for the PAEMST program—the highest recognition in the nation for a mathematics or science teacher. The Science Finalists will be recognized at the CSTA Awards Luncheon on Saturday, October 14, 2017. Learn More…

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

Thriving in a Time of Change

Posted: Wednesday, September 13th, 2017

by Jill Grace

By the time this message is posted online, most schools across California will have been in session for at least a month (if not longer, and hat tip to that bunch!). Long enough to get a good sense of who the kids in your classroom are and to get into that groove and momentum of the daily flow of teaching. It’s also very likely that for many of you who weren’t a part of a large grant initiative or in a district that set wheels in motion sooner, this is the first year you will really try to shift instruction to align to the Next Generation Science Standards (NGSS). I’m not going to lie to you, it’s a challenging year – change is hard. Change is even harder when there’s not a playbook to go by.  But as someone who has had the very great privilege of walking alongside teachers going through that change for the past two years and being able to glimpse at what this looks like for different demographics across that state, there are three things I hope you will hold on to. These are things I have come to learn will overshadow the challenge: a growth mindset will get you far, one is a very powerful number, and it’s about the kids. Learn More…

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Written by Jill Grace

Jill Grace

Jill Grace is a Regional Director for the K-12 Alliance and is President of CSTA.

If You Are Not Teaching Science Then You Are Not Teaching Common Core

Posted: Thursday, August 31st, 2017

by Peter A’Hearn 

“Science and Social Studies can be taught for the last half hour of the day on Fridays”

– Elementary school principal

Anyone concerned with the teaching of science in elementary school is keenly aware of the problem of time. Kids need to learn to read, and learning to read takes time, nobody disputes that. So Common Core ELA can seem like the enemy of science. This was a big concern to me as I started looking at the curriculum that my district had adopted for Common Core ELA. I’ve been through those years where teachers are learning a new curriculum, and know first-hand how a new curriculum can become the focus of attention- sucking all the air out of the room. Learn More…

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Written by Peter AHearn

Peter AHearn

Peter A’Hearn is the Region 4 Director for CSTA.

Tools for Creating NGSS Standards Based Lessons

Posted: Tuesday, August 29th, 2017

by Elizabeth Cooke

Think back on your own experiences with learning science in school. Were you required to memorize disjointed facts without understanding the concepts?

Science Education Background

In the past, science education focused on rote memorization and learning disjointed ideas. Elementary and secondary students in today’s science classes are fortunate now that science instruction has shifted from students demonstrating what they know to students demonstrating how they are able to apply their knowledge. Science education that reflects the Next Generation Science Standards challenges students to conduct investigations. As students explore phenomena and discrepant events they engage in academic discourse guided by focus questions from their teachers or student generated questions of that arise from analyzing data and creating and revising models that explain natural phenomena. Learn More…

Written by Elizabeth Cooke

Elizabeth Cooke

Elizabeth Cooke teaches TK-5 science at Markham Elementary in the Oakland Unified School District, is an NGSS Early Implementer, and is CSTA’s Secretary.

News and Happenings in CSTA’s Region 1 – Fall 2017

Posted: Tuesday, August 29th, 2017

by Marian Murphy-Shaw


This month I was fortunate enough to hear about some new topics to share with our entire region. Some of you may access the online or newsletter options, others may attend events in person that are nearer to you. Long time CSTA member and environmental science educator Mike Roa is well known to North Bay Area teachers for his volunteer work sharing events and resources. In this month’s Region 1 updates I am happy to make a few of the options Mike offers available to our region. Learn More…

Written by Marian Murphy-Shaw

Marian Murphy-Shaw

Marian Murphy-Shaw is the student services director at Siskiyou County Office of Education and is CSTA’s Region 1 Director and chair of CSTA’s Policy Committee.