Tag Archives: technology

Flappy Bird Physics Is Real Life?

If you don’t already know, Flappy Bird is the hot new mobile game right now. The premise is simple: navigate the bird through the gaps between the green pipes. Tapping the screen gives a slight upward impulse to the bird. Stop tapping and the bird plummets to the ground. Timing and reflexes are the key to Flappy Bird success.

This game is HARD. It took me at least 10 minutes before I even made it past the first pair of pipes. And it’s not just me who finds the game difficult. Other folks have taken to Twitter to complain about Flappy Bird. They say the game is so difficult, that the physics must be WRONG.

https://twitter.com/ThatPuckBeaut/status/428781313433149440

https://twitter.com/maaddawwg/status/427833802140815361

 

So, is the physics unrealistic in Flappy Bird?

Sounds like a job for Logger Pro video analysis! I used my phone to take a video of Flappy Bird on my iPad. To keep the phone steady, I placed it on top of a ring stand with the iPad underneath.

IMG_20140130_141424614

(I’ve uploaded several of the videos here if you’d like to use them yourself or with students: Flappy Bird Videos.)

Then I imported the videos into Logger Pro and did a typical video analysis by tracking Flappy’s vertical position in the video. Sure enough, the upside-down parabolic curves indicate Flappy is undergoing downward acceleration.

FlappyBirdPosition

But do the numerical values represent normal Earth-like gravity or insanely hard Jupiter gravity? In order to do this, we need to (1) set a scale in the video so that Logger Pro knows how big each pixel is in real life and (2) determine the slope of Flappy’s velocity-time graph while in free fall, which is equal to the gravitational acceleration.

The only thing we could realistically assume is the size of Flappy Bird. If we assume he’s as long as a robin (24 cm), then the slope of the velocity-time graph is 9.75 m/s/s, which is really close to Earth’s gravitational acceleration of 9.8 m/s/s. Flappy Bird is REAL LIFE.

FlappyBirdAcceleration

So then why is everyone complaining that the game is unrealistic when, in fact, it is very realistic? I blame Angry Birds and lots of other video games. Repeating the same video analysis on Angry Birds and assuming the red bird is the size of a robin (24 cm), we get a gravitational acceleration of 2.5 m/s/s, which only 25% of Earth’s gravitational pull.

AngryBirdsRobin

In order to make Angry Birds more fun to play, the programmers had to make the physics less realistic. People have gotten  used to it, and when a game like Flappy Bird comes along with realistic physics, people exclaim that it must be wrong. As one of my students notes:

 

UPDATE 31 Jan 2014:
Inspired by a tweet from John Burk,

we made a video showing Flappy Bird falling at the same rate as a basketball:

Here’s what I did: We determined from the analysis above that Flappy Bird is about 24 cm across. Conveniently, basketballs are also about 24 cm across. So I had my physics teacher colleague Dan Longhurst drop a basketball so I could video it with my iPad. Dan just needed to be the right distance away from the camera so that the size of the basketball on the iPad screen was the same size as Flappy Bird on the screen (1.5 cm). Next, I played the basketball drop video and Flappy Bird on side-by-side iPads and recorded that with my phone’s camera. Once I got the timing right, I uploaded the video to YouTube, trimmed it, made a slow motion version in YouTube editor, then stitched the real-time and slow motion videos together to create the final video you see above.

UPDATE 1 Feb 2014: While the gravitational acceleration in Flappy Bird is realistic, the impulse provided by the taps are NOT realistic. Here’s a velocity-time graph showing many taps. When a tap happens, the velocity graph rises upward:

FlappyBirdConstantPostTapVelocity

As you can see, no matter what the pre-tap velocity (the velocity right before the graph rises up), the post-tap velocity is always the same (a bit more than 2 m/s on this scale). This means that the impulses are not constant. In real life, the taps should produce equal impulses, which means that we would see that the differences between pre- and post-tap velocities are constant.

TL;DR: Is the physics in Flappy Bird realistic? Yes AND no.
YES: The gravitational pull is constant, producing a constant downward acceleration of 9.8 m/s/s (if we scale the bird to the size of a robin).
NO: The impulse provided by each tap is variable in order to produce the same post-tap velocity. In real life, the impulse from each tap would be constant and produce the same change in velocity.

UPDATE 1 Feb 2014 (2): Fellow physics teacher Jared Keester did his own independent analysis and shares his findings in this video:

 

Edtech PR Tips

I’m not a PR guy. I’m just a teacher. But they say that if you want to be a disruptor, the best experience is no experience. So here goes…

1. It’s not about the technology. It’s about what students are empowered to do because of your technology. Show us how you take students beyond what they could do previously. Show student work (“Hey, look what this kid can do!”). Stop focusing on checkmarks, badges, data, dashboards, and slick UI.


2. Learning is social. Show students interacting with each other, questioning, helping, constructing — all as a result of using your technology. Don’t show kids glued to screens, headphones on, working en masse and in isolation. It’s creepy.

rocketship-charter-schools

The Learning Lab at a Rocketship school, where students spend 2 hours each day.

3. Don’t use phrases that signal you have simplistic views about teaching and learning. In particular: Learning stylesdigital nativesindividualized instruction, and content delivery.


4. Practices are equally as important as content. Show how you enable students to engage and grow in the core practices in math, science, and ELA.

PracticesVennDiagram

Credit: Tina Cheuk, tcheuk@stanford.edu [PDF (scroll to bottom)]

5. Show how you implement/compliment research-based practices about how students learn. Study up on these characteristics of effective teaching methods. Otherwise…


6. Run controlled, peer-reviewed experiments that use conceptual diagnostic tests to measure growth. We know most anything works better than (or as well as) passive lecture instruction. But how does implementation of your technology stack up to other evidence-based teaching methods? And be sure to use conceptual diagnostic tests, not final exams or standardized tests or failure rates. CDTs have been painstakingly researched and designed to measure true conceptual understanding rather than algorithm memorization. Without strong evidence, we’re just skeptical of your claims.

hake1

Hake’s analysis of 62 different physics courses as determined by gain on a physics conceptual diagnostic test.

7. Don’t contradict yourself. Your words should match your actions.


8. Show feedback and testimonials from students. In particular, have students demonstrate their deeper understanding and expert thinking that has been enhanced by using your product. Or perhaps your technology has decreased student anxiety and contributed to a positive classroom climate. However, don’t have students talk about shallow things such as raising grades and doing well on tests.

MyEconLab

Testimonials from Pearson/Knewton’s MyEconLab

9. There’s nothing revolutionary about old wine in new bottles. A digital textbook is still a textbook. A video lecture is still a lecture.


10. Read everything Audrey Watters writes. Everything.

Do you have any more edtech PR tips to share? Any more examples of bad PR? Any good examples? Thanks!

Video Analysis of a Bouncing Ball

ballbounce3

Nothing earth-shattering here. I just wanted to share the activity we worked on today, which was an introduction to quantitative energy conservation by doing a video analysis of a bouncing ball. (Up until now, we were only doing qualitative energy pie charts.) Here are the handouts and the video:

The graphs from the analysis are just beautiful:

HeightTime VelocityTIme EnergyTime

Lots to talk about in those graphs!

Feel free to edit and reuse the handouts as you see fit. They’re not perfect, but I figure it’s better to share them than having them collect dust on my flash drive.

PS: I’ll sheepishly admit that I don’t do the whole suite of paradigm labs in the Modeling unit to mathematically derive the energy equations from experiments. But we do some simple qualitative demos/experiments to discover what variables would be in those energy equations. We start by talking about how the further a rubber band is stretched, the more energy it stores. Then we launch carts into a rubber band “bumper” (i.e., big rubber bands from Staples and two C-clamps) to qualitatively see the energy stored.

In doing so, we see that the cart’s kinetic energy depends on its speed and its mass. (Or is it weight? What would happen if we repeated the experiment on the moon?)

For gravitational energy, we can repeat the experiment, but have carts rolling down an incline. Or use the rubber band to launch the cart up the incline. I’ve also dropped balls into sand and looked at the depth to which they get buried. Either way, we see that gravitational energy depends on height and weight. (Or is it simply mass? What would happen on the moon?)

For elastic energy, we already know it depends on the distance the rubber band is stretched. Then, we can swap out the rubber band in the bumper with a stiffer/looser one to see the effects of the spring constant on energy stored.

Then, after we predict what the energy equations might look like, I just give them the actual energy equations, or have them look them up. (Gasp! See Schwartz’s A Time for Telling, aka Preparation for Future Learning.)

So, modelers, what am I missing by not doing the full-blown energy paradigm labs? How do you introduce the quantitative energy equations?

Going Beyond the Physics Textbook

I have the honor of being invited by Discovery Education to attend their second “Beyond the Textbook” forum to be held this Wednesday and Thursday at their headquarters in Silver Spring, Maryland. The event is spearheaded by Steve Dembo and, in exchange for travel expenses, he gets to pick my brain about digital textbooks, resources, and curriculum. There will be 18 other outstanding educators as well, including my edu-heroes  Christopher DanielsonMichael DoyleKarl Fisch, and Tom Woodward.

In preparation for the event, I’m updating/remixing an old blog post I wrote called “My Vision for a Physics iBook” ….

~~~~~~

I keep thinking about what a physics iBook would look like. Not a book for consumption, as with a traditional text, but rather a book to enable exploration. So what would a student see when they first opened such a book?

It’s blank.

No content. No classical references like Feynman’s Lectures on Physics. No integration with Khan Academy’s video library.  Nothing.

Why?

Students should be learning to do science, not simply learning about science. They should be making observations, posing questions, conducting experiments, finding patterns, analyzing data, and sharing their conclusions.

In this sense, the iBook would function more like an electronic lab notebook. As with curricula like Modeling Instruction and ISLE, students would create the physics content from their own investigations and evidence, rather than deferring to authority.

Actually, the iBook wouldn’t be completely blank. While it would initially be empty of content, it would be chock-full of tools to help students collect and analyze experimental data. Software like Tracker for video analysis, VPython and GlowScript for computation and visualization, LoggerPro for graphing and electronic data collection, along with PhET simulations and Direct Measurement Physics Videos for conducting virtual experiments.

In the realm of traditional physics textbooks, only a few make it a priority to incorporate experiments into their storylines. Three that come to mind are:

The Manga Guide to Physics

Picture2

Understanding Physics

FIGURE P-2  Electronic temperature sensors reveal that if equal amounts of hot and cold water mix the final temperature is the average of the initial temperatures.

and PSSC Physics.

Eugenia Etkina‘s upcoming College Physics text gets a step closer to my iBook vision. The text incorporates her work with video experiments in her ISLE and Physics Union Mathematics curriculula. In the text, there are QR codes which link to videos of the experiments to be analyzed.

For example, here’s a video of a momentum experiment, followed by the corresponding section of the text.

etkina

But, as you can see, the text does the analysis for the student. In my opinion, this would make a good reference only after the student has completed a similar activity on their own. Fortunately, her text also comes with a workbook that asks students to do this sort of scientific reasoning on their own:

activephysics

Also taking the “experiments first” approach is Live Photo Physics Interactive Video Vignettes, a collaborative project by well-known physics education researchers Robert Teese, Priscilla Laws, and David Jackson. During a vignette, students are asked to make predictions and do video analysis on-the-fly. Here’s a preview:

Science is never done in isolation, however, so the iBook would come equipped with tools for sharing data, content, photos, videos, and resources among students and between teacher-student.

For me, going beyond the textbook means giving students a toolbox rather than an instruction manual.

What’s your vision for the future of textbooks?

You can follow along with us at the Beyond the Textbook forum this week by searching for the Twitter hashtag #BeyondTextbooks.

Bonus: 5 reasons why iPads won’t replace textbooks in science class.

PhotoGrid_1363733048460

Projectile Motion Assessment Task

You are a game designer for Rovio Entertainment, the company that makes Angry Birds.  The human resources department wants your input. They are hiring several programmers to build the physics engine for Rovio’s newest game. Here are the demo videos from the top four applicants. Which applicant(s) would you recommend for hire?

Applicant A

Applicant B

Applicant C

Applicant D

Download the original video files for analysis in Logger Pro or Tracker.

These videos were not created by me. I found them online several years ago, but I can’t remember where. If anyone knows, please tell me so I can give the creator proper credit. Thanks!

VPython Screencasts

This year I’ve decided to have my AP Physics C students (15) make screencasts explaining the workings of and reasonings behind their VPython programs. I got the idea from college physics professor Andy Runquist, who makes his students do similar screencasts for their Mathematica assignments. What I like about screencasting is that it gives added insight into which students understand the physics and the coding of their programs and which do not.

We’ll be using Screencast-o-matic because it is easy to use and it’s web-based (no software to download and install). Another reason is because Screencast-o-matic allows for “open submissions” — i.e., students can record and submit their screencasts directly to a designated channel without having to create an account or upload their video to YouTube. Which is great because all the screencasts will be in one place and I don’t have to worry about getting/managing links from students.

To help students with screencasting, I’ve made a tutorial video, along with examples of good and bad screencasts.

Screencast-o-matic Tutorial

Low Quality Screencast

High Quality Screencast

Happy Screencasting!

My TEDxNYED Session: Learning Science by Doing Science

Many thanks to the TEDxNYED 2012 crew, especially True Life Media, Basil Kolani, Karen Blumberg, and Matthew Moran for an awesome event. Be sure to check out the rest of the TEDxNYED 2012 talks.

Learn more about Modeling Instruction in Science.