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Monday, August 24, 2015


Welcome back to ETHS for the 2015-16 school year!! We will have a LOT of fun while learning a bunch of physics and how it relates to your lives and to the way the universe works.

Doc V's schedule is:
   3 Chem-Phys periods 1-2, 6-7, 8-9
   AP Physics C periods 3-4
   Free period 5

Friday, August 21, 2015

Pendulum Lab Training Video for CT-STEM

One of the lessons for the CT-STEM Project in physics is a classic, that most physics classes will do in mechanics: the simple pendulum. While this is a 'simple' experiment to run, this video outlines how to add in numerous computational thinking (CT) skills, which in turn will also address a number of bullet points within the Next Generation Science Standards (NGSS).

One point of emphasis is to have students do labs like this before formally studying the subject - we want students to do more of the process of science, and discover rules and principles of phenomena on their own, where these findings and student questions about the lab drive classroom discussions. In this case, students will need to do up to four individual controlled experiments to determine how the period depends on mass, length, angle, and the strength of gravity. By making plots, and finding best-fit functions through curve-fitting, students will develop an empirical formula (i.e. a mathematical model via data) for the period of the pendulum. They can then compare it to the accepted textbook formula, and get into good discussions of experimental uncertainties, scientific inquiry, building mathematical models, being critical of data, experimental design and methods, and so on.

It is also mentioned in the video that teachers can have students evaluate the effectiveness of measuring techniques - for one experiment use a stop watch, for a second an electronic force sensor, and a third video - for the period. And then, for gravity, the usefulness of computer simulations, using a PhET pendulum simulation.

Ohm's Law Lab Training Video for CT-STEM

One of the physics activities for the CT-STEM Project at NU is an Ohm's law lab. While not terribly complicated for students to do, the main point being made is for teachers to have students try this lab as a first-step when beginning a unit on basic circuits. Most students have little electricity knowledge or experience, and most have not heard of Ohm's law. By having students do this first, they can use real data to 'discover' how resistance and voltage affect electric current. Best-fit functions of those data will allow students to at least reach some conclusion of an empirical formula, which should be close to I = V/R.

This type of process, where labs are done first in units and students use data to find empirical relationships and equations through the use of computational thinking skills, will truly help our efforts addressing Next Generation Science Standards (NGSS).

An additional chance to apply computational thinking skills to this lesson is this PhET video on Ohm's law (especially if a school does not have the equipment to do the physical experiment), or a Netlogo simulation for resistance, where an electron can be isolated as it bounces its way through material.

Thursday, August 20, 2015

CT-STEM Lesson Notes: PhET Resonance Computer Lab

With science classes around the country being responsible for the Next Generation Science Standards  (NGSS), teachers will need to develop more labs and activities that get students doing the process of science, rather than learning just science facts and being given information - students will need to 'discover' some portion of the material studied in the class.

This example is for a computer-based lab from the PhET library, and it deals with a topic students will almost certainly not know, resonance. Students can do a series of controlled experiments, trying to see what combinations of mass, spring constant, amplitude, frequency, and even gravity, have on the system reaching a resonance state, where the oscillator and mass are in phase with each other. Being a computer simulation, there are also numerous computational skills and concepts that are addressed.

Variations of this could include students making a screencast of their experimental sessions, and then using Tracker or another video analysis package to get finer details and measurements, by having frame-by-frame options and so on. This type of simulation exercise can allow for many good conversations about experimental design, data collection (especially when the springs are going through transient phases in the simulation), and reaching conclusions when there are multiple physical parameters that might affect the spring oscillations. All of these types of skills and experiences fall under NGSS, and these are all computational thinking skills on top of it.

Whether it is this specific lesson or not, teachers can set up numerous other simulations in the same way to develop a set of CT lessons that address NGSS requirements.

How to do Video Screencast and Analysis of a Video Game to Determine the Physics

One of the primary tools STEM classes have to analyze various phenomena is video. With the cameras on cell phones, for instance, many new devices have high-speed options for video, such as up to 120 or 240 frames per second (fps). The same for most cameras and camcorders one can purchase as the prices come down.

This video gives another fun option to do some physics while playing video games. When playing an online game, you can use Screencast-o-matic to create a screencast video of you playing the game for a few seconds. Screencast-o-matic is nice because you can use it for free and do not have to download anything - just click 'Start Recording' and it begins!

With that video, you can import it into a program called Tracker, which can be downloaded onto your computer for free. Some schools may have Logger Pro, which is the software for Vernier sensors, and that has video analysis capabilities. Whatever the tool, check this out to see how Tracker can be used within a few minutes to get data for the game Asteroids, to find the speed of the spaceship. You can set size scales to make the scene as realistic as you wish. In the case of Asteroids, you can look up average sizes and densities of asteroids, find the size within the video game based on your size calibration and scale, and then determine the masses of asteroids. You could look up and use a reasonable size and mass for a spacecraft (many often use the space shuttle, looking it up in Wikipedia). Then, with those data, you can calculate speeds from motion graphs in Tracker, which leads to accelerations, forces, momenta, kinetic energies. You could calculate the gravitational forces between asteroids and your ship - are those significant? If so, does the video game account for those forces, or is gravity ignored? You could have some fun and calculate how much you would weigh on one of the asteroids, and what the escape velocity is - would you be able to jump off the asteroid and into space?

You could do a similar process and analysis with a billiards video game - and then determine from measurements in Tracker whether or not momentum is conserved, or if energy is conserved, and so on. You could also take video of a real game of billiards, or anything in life that has motion, and begin analyzing the video to see the physics! It is a really useful and powerful tool we can use for anything in life and any experiments we do in class. I hope this helps!

Thursday, August 6, 2015

Water Use and Aquifers in the U.S.

A new study from a research group at the University of Illinois at Urbana-Champaign (UIUC) and Lehigh University, led by civil and environmental engineers, have tracked water use taken from three of the most used aquifers in the U.S.  Fresh water is, of course, becoming an issue in the U.S. as well as around the world as the population is expected to go from a little over the present 7 billion people to 9 billion people by 2050. Understanding how and where the water taken from all supplies, particularly those from the more major water sources such as these three aquifers, is vital for policy makers as they plan for the future. There are all sorts of tradeoffs that come with such decisions, and this is where politics will play the key role in deciding who gets what with our most precious resource. This involves where and how many people can settle in communities, agriculture, economies (both local and global), a huge variety of industrial uses, and transportation; all of these sectors of our society have large lobbies that will try to sway votes to their cause, so one can imagine the pressures decision-makers are under and will be under in the next couple decades.

Check out an article about the study here. There is a nice graphic that helps understand where the water goes. The published study can be found here. This is a good way to see another aspect of what engineers do.