Category Archives: Physics Demonstrations

ISTE 2013, ScienceOnline 2013, and GAME Webinar

Yours truly will be making a few public appearances in the upcoming months as I, along with two other educators, travel the country (a little bit) expounding on the idea of video games as classroom tools.

First up, this Thursday night, I’m going to be interviewed by the fine people of Gamers Advocating Meaningful Education (G.A.M.E.) as part of their Guild of Educators series. You can watch the livestream of the webinar and ask questions as Steve Isaacs, Lisa Castaneda and I discuss how we have used Portal 2 in our respective classrooms. Steve is a video game design and development teacher in New Jersey and Lisa is a math teacher in Washington state.

Later this month, I’ll be travelling to Raleigh, NC to discuss Portal 2 in the classroom with Erik Martin as part of ScienceOnline 2013. This will be my first time at ScienceOnline. It sounds like a cool conference. I’m expecting a lot of audience participation while we discuss video games as classroom tools.

And now the big one. This summer, Steve, Lisa and I will be presenting at the prestigious ISTE 2013 conference in San Antonio. Our presentation is entitled “Learn with Portals: STEM Education Through Gaming.” We’re really excited to share our approaches to Portal 2 in the classroom with a national audience. I’ll definitely have more information about our presentation and the conference as the conference date approaches.

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am i the cool kid now?

Portal 2 is gaining traction amongst high school students! Check out this informative overview of Teach with Portals (with a few quotes from yours truly) posted by a motivated and enterprising 10th grade student on her high school’s blog.

New toys in the puzzle maker!

Valve released some new items for the educational build of the Puzzle Maker! Here’s a rehash of some older videos about momentum and collisions using the new toys.

Bonus feature! Check out this crazy oscillator device I made with contraption cubes of different masses. It’s pretty mesmerizing. The cubes get heavier from left to right but the strength of each aerial faith plate is the same.

Here’s a quick high school physics lesson.

My oscillator reminds me of the wave pendulum in the video below because both systems show repeating patterns. The swinging billiard balls form a wave with varying frequency. My oscillator also appears to be demonstrating wave-like properties.

The billiard ball pendula are oscillating on strings of varying lengths but are pulled to the same angle. The period (time of one oscillation) of a pendulum pulled back to a small angle is

Period = 2Π√(length/strength of gravity)

So, if you increase the length of the pendulum, you increase the period. Each progressively longer pendulum takes a bit more time to make one period in the same way that each progressively lighter companion cube stays in the air a bit longer. Of course, the game’s oscillations aren’t perfect. I’ll take another look at the differences between the way the cubes are bouncing and how they should bounce to determine the exact variations between the physics of aerial faith plates in the game and similar launchers in real life.

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an even closer look at air resistance

I took a deeper look at my experiment from the last few posts and made a couple graphs.

The first details the difference between predicted and actual values for the magnitude of the cube’s velocity as it flies through the air:

Notice how the actual data strangely has a small dip at the beginning. I’m not sure where that’s coming from. Let’s take a look at its X and Y velocities:

The predicted values run a little bit farther than the actual values because I let my simulation (i.e. Excel formula) run a little bit longer than it takes for the cube to hit the ground.

There seems to be a weird jolt around 0.2 s. I’m not really sure what’s going on here. If you’ve got any ideas, please let me know.

I also looked into the difference between predicted and actual values for the height of the cube as it flies through the air:

I had to eyeball the height of the cube as it fell, which led to the wonky graph line. Regardless (and unsurprisingly), it still appears as if it takes a little bit longer for the cube to hit the ground than is predicted. It’s safe to assume that this is because of air resistance.

Any ideas about what’s going on here? Any ideas for new tests? Let me know!

I apologize for the dearth of posts lately. School started this week (!) so I’ve been insanely busy. I’m planning on giving my students their first hands-on experience with Portal 2 in about two weeks. They’ll be running labs that have been almost a year in the making. Of course, anything and everything that happens with portals in class will be documented here. Stay tuned.

the velocity limit of portals

Hello everyone coming from Singularity Hub! Check out my demonstration videos for a good overview of what I’m trying to do. And for the educators out there, take a look at my lesson plans and let me know what you think!

After my last post about the effect of portals on cube velocity, I was asked about the actual velocity limit for cubes moving through portals. It’s easy to calculate. Looking at my Portal Velocity Limit Spreadsheet, it’s clear that any cubes dropped farther than about 8 panels were slowed to the same velocity as they passed through the portals. To get an idea about the portal velocity limit, we’ll start with the equation:

v_{max}=\frac{\Delta x_{max}}{t}

From the spreadsheet, we’ll be using \Delta x_{max}=11.25 panels and t=1.53s, which gives us v_{max}=7.35 panels/s.

Of course, that doesn’t take air resistance into account, so we really just found an average velocity. To find the instantaneous velocity of a cube as it passes through the portals, we’ll be using the console command, “physics_debug_entity.” Check out the video below.

It looks like our results make sense. We would expect the instantaneous velocity of a cube when it first leaves the portal to be higher than its average velocity after being slowed down by air resistance.

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