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Monthly Archives: August 2013

What’s the Problem?: Air Cannon

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While the school year ramps up, I’ll try to post a couple things I’ve used in class in the past. In the upper Midwest (mostly), there’s a chain of sandwich shops called Erbert and Gerbert’s. In part because of how late they delivered, a lot of my limited-college-money was given to them, quite happily, in exchange for soup or submarine-themed-subs. The best part is that they pinch out the squishy middle part of the bread to make room for fillings, and give you the “guts” alongside your main meal. Now I’m hungry.


E&G is also known for their somewhat strange commercials. Besides having a pig as a mascot, their commercials were usually pretty (wonderfully) strange. Take this one, for example.

Act 1: Observations and Hook

I use this video during Newton’s Laws of Motion. It could also be used for some other mechanics-related topics.

Act 2: Questions, Possibilities, Resources

  • What the what??
  • Where do you see Newton’s Laws in the video?
  • Would the air cannon still work without the fog/smoke stuff?
  • If you make the shape of the output hole square, what will the vortex look like?
  • What does inertia have to do with how the smoke ring forms?
  • List basic parts (or draw a schematic) of air cannon parts.
  • How does the length of the barrel affect the speed of the vortex?
  • Why does the size of the vortex grow as it travels?
  • What would you change in the cannon to get a slower-moving ring?
  • How does air have enough force to knock things over?
  • What if you put confetti inside?

Act 3: Resolution and Continuation

  • It’s pretty easy to make your own air cannon. The second link actually has a number of answers for Act 2.
  • Propose your own air cannon design using a cardboard box and any other materials.
  • Would a similar-sized cardboard version of the video air cannon have the same power/speed/force?

In case you love this video as much as I do, here’s the behind the scenes video of how they made the air cannon (plus a flash of math, a quick conversation with a physicist, and some sandwiches).

What’s the Problem?: Hourglasses

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A la Dan Meyer‘s Three-Act Tasks, I’d like to try a few science-related ones. I think a lot of Mr. Meyer’s scenarios could be science-y, but in the context of math class, they’re math-y. Actually, his method for creating the Task is pretty close to Scientific Method, i.e., observe a Thing, wonder, test. Booya! science for the WIN!


Maybe this is just a version of discrepant events. This particular one isn’t terribly discrepant, but maybe it’s a little strange. Here’s the first (I hope) of a series I’m going to call, “What’s the Problem?”

Act 1: Observations and Hook

There are a lot of possible questions here. It’s almost toward a 101qs-type thing instead of a particular task.

Act 2: Questions, Possibilities, Resources

  1. List all of the parts seen in the video. List other characteristics of the hourglasses.
  2. Why so many hourglasses?
  3. How long do they run?
  4. Are they supposed to be the same time length?
  5. Is the one with the most sand the longest?
  6. Does the sand fall at the same rate for each hourglass?
  • Hourglasses each have a clear barrel, black end-caps, and some amount of sand. Characteristics that might differ include the width of the barrel, the width of the narrow opening between top and bottom.
  • There’s a board game that came with these ten hourglasses.
  • They vary in timing-duration from 25 seconds to 1:07 minutes, according to my stopwatch.
  • They are all supposed to be one minute timers.
  • The one with the most sand is not the longest timer-length (it runs about 1 minute) The one with the least amount of sand, however, is the shortest.
  • Sand does not appear to fall at the same rate (the shortest duration hourglass appears to pile up more quickly than the rest).

Act 3: Resolution and Continuation

In order, the duration of the hourglasses looks something like this:

hourglasses in order of duration

0:25, 0:50, 1:00 (x3), 1:01, 1:02, 1:04 (x2), 1:07
Note: that the amount of sand does not appear to increase consistently as duration increases

  • Only three of the ten hourglasses actually run for one minute (although two others run 1:01 and 1:02).
  • How might this potentially affect game play for the board game?
  • Why doesn’t the amount of sand seem to matter for duration (i.e., other factors in falling sand)?
  • Could we make them all into the one-minute timers with current materials?
  • If we could open all of the timers and make them equal duration, what would that time be?
  • How might these hourglasses have been made in the first place, since they are not terribly accurate?
  • Would weighing them help?
  • How would a different grit of sand help or hurt?
  • Would a different color of sand help the stopwatch-holder (and board-game-player) see the endpoints better?

Back to School Time — Hooray!

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It’s August, which means that the first school bell of the year is coming soon. And huge secret here I’m looking forward to it!

As a student, I was not excited by the prospect of yet another year in classrooms (even though there’s very few things that can trump the smell of a new box of crayons). But, as a teacher, I really like doing my job. I like working at something that’s challenging and interesting and constantly changing. A lot of my teacher-friends groan about the new school year and how the end of summer is drawing to a close, but I know that they’re secretly counting down the days to a new batch of kids in their classrooms.

But what makes us do it? For me, it was a matter of finding what made me tick. I truly love teaching, and am glad I found it. A few years ago, I realized that everybody remembers taking high school chemistry, and that they had a fantastic or terrible teacher (somehow, there’s no middle ground). But most of all, they remember the experiments and explosions that teacher did. I get to be that teacher! (and hopefully I am on the higher end of the teacher-rating scale than the awful side.)

So, what makes other people work at what they do? What was the story that got them into their eventual careers?

At The Origins Project, hosted by Arizona State University, a panel of mostly-science-related speakers told stories of how they got into their respective fields. I was slightly disappointed that they didn’t talk more about how to tell the stories in science, but the stories are also fascinating because of how well they’re told. Here’s the approximate times for each speaker, in case you’d like to skip to certain people:

9:00 min — Lawrence Krauss, physicist, cosmologist, and host of the panel
15:17 — Tracy Day, journalist and co-founder of the World Science Festival
23:30 — Brian Greene, of The Elegant Universe fame
33:50 — Ira Flatow, host of Newton’s Apple when I was a kid and Science Friday on NPR now
40:35 — Neil deGrasse Tyson (I don’t really have to introduce him, right?)
55:20 — Richard Dawkins, evolutionary biologist
1:05:35 — Bill Nye (another man who needs no introduction)
1:15:10 — Neal Stephenson, sci-fi author

For what it’s worth, I really enjoyed Ira Flatow, Dr. Tyson (of course), and Neal Stephenson’s stories.

What gets you up in the morning, and how do you tell it so that others want to know more?

Grading Regrets

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Dear former students,

I started teaching at a fantastic public school. A really big one. One where the staff genuinely cared about the kids, standardized testing be damned. There were a lot of “at-risk” kids and ELL kids and minority-group kids, and the staff really tried to help out each individual. So I tried to do my part, with my neat little syllabus and all of my classroom rules.

And I hated grading.

Now, that’s not very significant. I don’t know any teachers who enjoy grading. But besides the monotony of searching through papers and lots of green ink (red ink’s not my thing), what I really hated was assigning those letter grades at the end of the term. And the biggest reason it ticked me off was that for the kids who really worked their hardest and the kids who just didn’t care, that letter grade often looked the same. It sucks. It really bothered me. And I wanted to reward massive effort, but I just didn’t know how.

But also, I didn’t know how to reward effort while keeping a this-is-the-proficiency-of-the-student-in-science intact for transcripts. Those similar-looking letter grades that meant very different things made me angry and frustrated, and there was more than one evening spent stomping around my apartment, aggravated and impotent. I wanted to add notes to all of the grades explaining the difference between this C-grade and that C-grade. And even if I did know what to do, that first year of teaching is all about survival, and I couldn’t find the time.

I’m so sorry.

At least I didn’t grade the way the Malcolm in the Middle teacher did, with a forced curve and fractional points.

Still, there must be a better way. I want to change!

I’ve been researching Standards Based Grading, and it sounds a lot more like something I’m comfortable with. I’ve read some Marzano and this and this and this and this.

I know it won’t help you, my former students, but hopefully I’ll be able to grow from it.

Thank you for teaching me.