Accuracy vs. Understanding

Let’s say you’re teaching a Grade 8 or Freshman level class. Algebra 1-ish. You’ve got some data here.

x y
1 3
2 5
4 10
6 10
8 12
10 17

You want to show how data may be modeled as an equation. We could go about this two ways.

We could follow some TI-84 instructions via a handy dandy set of instructions.

We could also do something like this in Desmos, using the sliders feature.Students would be asked to manipulate the sliders until they think they have the line of best fit.

Discussion questions:

  • Which of these activities leads to the more accurate answer?
  • Which of these develops a better understanding of how a data set may be represented by an equation?

I wouldn’t say that conceptual understanding and accuracy are always juxtaposed, but it seems that they sure can be. I think I’ll leave it at that for now, but I’m a bit terrified to pursue this line of thinking much further. There might be drastic implications that I’m not sure I’m emotionally ready to handle right now.

Posted in Uncategorized | 11 Comments

If the sun is an 8 foot diameter balloon, what is Pluto?

Artifacts

The following clips are cribbed from Nova: The Pluto Files in which Neil deGrasse Tyson sets up a model of the heavenly bodies of our solar system, comparing their sizes relative to the sun and each other. Not all of the clips were able to be chopped to give the appropriate bleep sound. So we just have a few. More on that in a moment.

Side note: for the record, if you want to see a kid from the age of 4 to 14 get animated about something, tell them that Pluto isn’t a planet and/or let them watch this episode of Nova. They’ll go berserk. Neil’s right: people are crazy when it comes to Pluto’s planetary status.

Anyway, on to the entry events.

Intro & Mercury

Saturn

Pluto

Bonus!: Diameters of Uranus vs. Pluto

I’m not sure you need all three or four of these for kiddos to get the point. And I’d get some predictions on the board before having students explore this on their own or make and calculations.

The Process

  1. Show the Intro & Mercury clip
  2. Get some predictions.
  3. Reveal just the Mercury solution. Show some of the calculations involved. You can find all the heavenly body sizes from our solar system here or here.
  4. Show the Saturn clip.
  5. Let students make some predictions and do some research on the actual sizes of the heavenly bodies. More predictions on the board.
  6. The big reveal. For the solutions, you can just watch the clip straight from the home site linked above.

Here’s a potential accompanying worksheet.

Possible Extension

Neil says that we can’t properly represent the distance of the planets from the sun on this scale of a field. So my question is, how could we represent a scale model of the planetary orbits and distances from the sun?

Here we have Mercury five yards away from the sun. If Mercury is 5 yards away, how far away would Pluto be then?

field ss

Posted in astronomy, proportion, volume | Leave a comment

Hot Rod Quadratics: Let’s jump this jump!

Artifact

Hot Rod is one of those movies that’s incredibly dumb the first time watching it. The second time watching it, it’s still incredibly dumb, but it gets funnier with each passing viewing. It’s basically just an excuse for Andy Samberg to to Andy Samberg things for 90 minutes. I’m ok with that.

Anyway, this isn’t Rotten Tomatoes. Let’s get to our Entry Event:

The final stunt of the movie, cut ever-so-slightly short.

Suggested questions

  • The most obvious one: will Hot Rod land the jump? Or maybe better if you know how it ends: will he clear the jump?
  • You could get all physical on this question. Considering how high he is and how fast he’s going at liftoff might be some other options.

Activities

In a nod to Dan’s “Will it hit the hoop” task, I’d go with Geogebra here as well. In fact, let’s just use pretty much the same idea (side note: if anyone can rip a better quality video, I’d be interested).

hrgeogebra

In fact, I’m going to go ahead and toss it in after the Basketball task in my Algebra 1 curriculum map. I’d consider using the Hot Rod task as a way of solidifying conceptual understanding by removing some of the sliders on the Geogebra task, or removing it from Geogebra entirely and having groups do some hand-to-hand combat with it on paper. It’s times like this that a problem taxonomy could help: do you want to assess student learning or enhance prior learning?

The goods

The video (above)

A couple screen shots

Fig 1:

jump1 jump2

Figs 1 & 2 mashed together

jump12

The Geogebratube student worksheet

Aaaand the “reveal”:

On final monkey wrench:

hr_jump3

Conservation of momentum?

Posted in quadratics, Uncategorized | 2 Comments

Let them get it wrong: Caloric Quandary

Artifact & Facilitation

I must have cylinders on the brain. Maybe because they’re actually one of the few traditional geometric shapes that we actually interact with on a regular basis? Maybe it’s because they’re readily measured?

Anyway, here have a Coke can and one of those mini-Coke cans. Though it’s dependent on you exactly what information you’d like to black out.

You could black out one of the calorie counts and compare it to the fluid ounces.

small_calorie

You could black out one of the fluid ounces counts and compare it to the calorie counts.

large_oz

You could eliminate the fluid ounces and one of the calorie counts to get at a really nice volume comparison (though, you’ll need additional dimensions – that’s good! Ask the kiddos what other dimensions you’ll need to procure?). 

both_oz_large_calorie

While you’ll need other dimensions, I would actually withhold the dimensions of the base at the beginning. Why? Because students of all ages have a real tough time with scale factor and volume. Like, REAL tough. As in, I tell them straight up “when you increase the dimensions by a factor, the volume increases by that factor cubed” and then they totally forget that by the time I’m done saying it out loud.

So let students solve it using a simple proportion.

image10

4/5=90/x –> x=112.5 calories

Then when you reveal the actual calorie count, we’re all like “wha?”

040

“Wha???!!”

040

“WHAAAAAA??!?!??!! Math is wrong! You lied to us!” Or maybe they’ll claim corporate conspiracies to get us all fat. Either way: win-win.

This is the part when you swoop in with some additional dimensions to save the day. Find the volume relations of the two cylinders, the calorie counts, and you’re home free.

rect3018

********

I also feel like there’s some way we can leverage this into some additional follow-ups/extensions: 

Or this.

********

I like having calorie counts as the final measuring stick for this task instead of volume.

Like I said, scale factor and volume (and area) were something my students would consistently get wrong. I think it’s indicative of the problem with front-loading instruction. Students don’t need to think deeply about the content because I’ve showed them how to do it in the “Scale Factor Unit” when it’s applicable, of course. Then, three months later, when we’re not in that unit any more, it’s out the window.

I’d suggest you read Frank’s post and watch the embedded Veritasium (@veritasium) video for more on allowing students to swim in their misconceptions a bit to enhance learning in the end.

Posted in proportion, volume | 1 Comment

What? How do YOU spend your two-hour school delays?, Water Content in a Snow Cylinder

As anyone in town for NCTM in Denver know, it’s been a bit snowy here this week. In fact, Fort Collins just had its biggest snowfall of the year. But how big?

We had a two hour school delay this morning as my daughter and I were greeted by this on our back doorstep.

001

“Wow that’s a lot of snow!” she says. But how much snow is it?  Go go gadget EmergentMath!

Artifact

I got this ridiculously large [cola] mug at a white elephant gift exchange last Christmas. And now I have a chance to use it!

004

I asked her to make a prediction on how full the mug would be after it melted. We each made a prediction using her hair ties (hers on top, mine on bottom).

009

We took a couple measurements just for posterity’s sake.

006007

008

I dunno, we might want them later. For now though, we just stuck with the predictions.

We then watched it melt. Slowly.

Sure enough, we were both way off:

013 015

Wow. All that snow and only that much actual moisture. I have some questions:

  • Is this typical? What if we redid this in the afternoon after the snow had packed a little more? 
  • What if we used different shapes? Could this be a sort of alternative to the how-full-is-the-weirdly-shaped-glass problem?
  • Going back to the original photo, how much water was on that table?

I also have a couple comments:

  • Want an easy way to build buy in? Have kids make predictions on something and make sure it *takes a long time* for them to see if they’re right. Like I said, our delay was a couple hours and this pretty much took up the entire time. This was sort of analogous to Dan Meyer’s now-famous water tank filling task.
  • This seems ripe for Estimations 180.
  • I’m not sure what you could do if you live in a non-snow state. What would Texas use? Sand? Cicadas?

My daughter and I could have gone into the volume of the near-cylinder, which dimensions were useful and that sort of thing. But our two hours were up. It was time to go to school.

Update 4/16: I’ve got my Facebook friends eating out of the palm of my hand. *maniacal laugh*

predictions

***********

Sort of related: a couple atmospheric scientist friends of mine started a Facebook page crowdsourcing, archiving, displaying, and discussing clouds: Community Cloud Atlas 

You should join their Facebook page and tell them to get a twitter account.

 

Posted in atmospheric science, predictions, volume | 5 Comments

Here are your Algebra 1 and Geometry Problem Based Learning curriculum maps.

Yes, you can do wall-to-wall PrBL. Yes, you can align your PrBL curriculum to Common Core standards. Yes, you can do it all with the help and goodwill of the math twitterblogosphere.

Note that these are just the tasks. They are not the facilitation notes, the scaffolding, the assessment. Just the tasks and problems provided for students that you could potentially work through. Also, this is just the free stuff. So that means no Dana Center, no Mathalicious, though I’d encourage you to check out both resources and consider paying them for the quality work they produce.

Check it out.

And with that, it’s probably time to shutter the Great Inquiry Based Math Curriculum Mapping Project. It hasn’t gotten too much traffic lately. And honestly, we’re past the point of just ideas for problems. It’s time to create and improve them.

Enjoy!

Posted in Uncategorized | Tagged | 2 Comments

Inheriting the wind; these are two of my favorite books about math

177

Baseball Prospectus

I never liked baseball as a kid. Maybe it’s because I wasn’t any good at it. Maybe it’s cause I never went to a professional game. Maybe it’s because it is quite boring when you watch it on TV. Then in the late 90′s the sabermetric revolution upended the stuck-in-the-50′s baseball establishment by using data to prove and disprove various myths that were pervasive in the game. From roster construction to in-game tactics, the sabermetric community was one or two steps ahead of the rest of the game. It was this data-driven analysis that served as my entry point into the game. Eventually the data-movement coalesced under the Baseball Prospectus name. Housed at baseballprospectus.com, the writers produce an annual that is my notice that Spring has arrived.

179

The annual contains copious amounts of raw numbers, advanced metrics, data tables, projections, as well as an approachable and easy-to-digest writing style that I blast through every March. This year was no different. This is one of my favorite books to read every year.

Measurement

Here we have another book grounded in mathematics: Paul Lockhart’s Measurement. Here we have a rich text of mathematical creativity and imagination. In fact, pretty much everything in the book is developed in the author and reader’s imagination.

061

The problems posed (some of which even have Lockhart’s proof to accompany them), are decidedly abstract in nature. The problems rely on ingenuity for a solution. Lockhart is more likely to use mental shape-folding than a two-column proof to describe a mathematical concept, let alone a spreadsheet of data. This is one of my favorite books.

Both of these books (in Baseball Prospectus’ case, the annual publication) are quite dear to me. They also represent two entry paths through mathematics. One uses messy numbers and data to explain why things are the way they are. The other uses clean, imaginary shapes to explain why things are the way they are in our imagination. They both feature clever, humorous, conversational writing including analogies and storytelling.

Inherit the Wind

Then there is the final scene of Inherit the Wind. After psuedo-successfully defending a high school teacher who dared to teach evolution in the classroom, the protagonist of the true-story, defense attorney Henry Drummond picks up the Bible in one hand, Darwin’s The Descent of Man in the other, and exits the courtroom. Both of these books reveal things about the nature of man, and you’d be a fool to entirely discard either.

There are context-rich ways of posing mathematical tasks. There are entirely abstract ways of posing mathematical tasks. There are interesting and engaging ways of posing problems. There are dry and uninteresting ways of posing math problems.

I hated math in high school. All the way up until my integrated Physics/Calculus class threw an old computer off the football stadium and recorded it on video and we were able to successfully approximate the gravitational constant. I’m not sure if I had been presented abstract math in more interesting ways I’d have latched on to it. I was a pretty detached kid. It’s possible, but I was also more prone to think about mid-90′s Indians baseball and Carlos Baerga’s VORP. That would have been a way for me to engage with mathematics in High School. In fact, I did engage in it when Rob Neyer would publish a new column. But that was me.

I’m not saying that every task needs to be grounded in the real world. But the number of contextual mathematical tasks that should be provided any given year is certainly greater than zero. It’s probably greater than 10. Maybe the tasks need not even be that authentic. I mean, is throwing a computer off a building a “real-world” situation? Or was it just a fun thing to do that we then did a bunch of math on? It was “real-world” in the sense that we saw it happen. We interacted with it physically, visually, inter-personally  and mentally. I have not, to this day, had a professional reason to toss a computer off a stadium.

Mathematics is so wonderful and ubiquitous that anyone can have some sort of entry point into the subject. It’s too vast to be constrained to a single context or a single person’s imagination. Our access points to the subject change from person to person, from age to age. You’d be foolish to eschew context-dependent scenarios to explore mathematics. You’d be foolish to toss aside all imagination from the content. You’d be foolish not to explore any and all avenues of all ways to provide access to this remarkable subject to your diverse students. You’d be inheriting the wind.

inherit

Posted in commentary, Uncategorized | Leave a comment

Evaluating energy efficiency claims

Artifact

This (or other) energy efficient light bulb package(s).

Energy Efficient Bulb 20-75 w

So many opportunities here, depending on how targeted you want to be. Or, if you prefer, what kind of problem you plan to facilitate. There’s a clear nod to systems of linear equations (when one compares the time of payoff). There’s also an opportunity for some simple, linear equation building: evaluate the truth behind the $44 claim.

I’m even thinking of a 101qs video in which a perplexed customer at a hardware store is comparing this light bulb, and, say, one of these, though, these existence of incandescent bulbs is probably not long for this world. And, being Easter, hardware stores are closed today (fun fact: also, retailers really don’t like it when you take photos and videos in their stores). But that brings up a whole other can of worms: how much energy will countries save by switching to energy efficient bulbs? Like I said, lets of ways to go about this, depending on whether you want to be targeted or more exploratory.

Suggested questions

  • Is that $44 claim reasonable or bogus when you compare it against a bulb that uses 75 watts?
  • How does this compare with other energy efficient bulbs at the old hardware store?
  • What would happen if you switched every bulb in your house/school/neighborhood to energy efficient ones?
  • How much does a kilowatt-hour cost in our town? And what exactly is a kilowatt-hour?

Potential Activities

  • Take some predictions: does $44 savings sound about right over 5 years? Is that too high? Too low?
  • Collect some data on how much your lights are actually on in your house.
  • Plot five years of bulb use and see what happens.
  • Go around your house and count the number of bulb outlets you have. That data may be nice to have on hand.
  • Tables, graphs, equations, the usual bit.

Potential Solutions

Not sure what electricity costs in your particular neck of the woods, but Planet Money suggests a US average of $0.12 per KW-hr. These 20 watt bulbs usually cost around $12 per bulb, give or take. So our function looks like:

cost=$12+(20 W)*(1 KW/1000 W)*($0.12/KW-hr)*hours

Incandescent bulbs go for about $2, and comparing with a 75 watt bulb, our graphs look like this.

I actually get a savings over 8000 hours of $42.8:

(2+75/1000×0.12x 8000)-($12+20/1000 x 0.12 x 8000). That doesn’t take into account replacing incandescent bulbs more often. You could potentially get all stepwise functions if you consider the, perhaps 1000-2000 hour lifespan of an incandescent bulb.

(note the slightly different guesstimations of numbers in the planning form)

Final Word. Pretty much anything involving energy efficiency is going to allow for some systems problems. It’s all about tradeoffs, with higher initial costs gradually replaced by energy savings. Water heaters, A/C Units, automobiles, window insulation, you get what you pay for.

Posted in algebra, equations, estimation, stepwise functions, systems of equations | 2 Comments

How does one provide the complex data of global warming to students?

Update (3/12/2013): An atmospheric scientist friend of mine, Katie, suggested a few edits to this post, primarily to clear up a few of the tools listed here. The edits are in bold.

My initial thesis on this post was originally going to be “why don’t teachers let students investigate global warming very often?” While this may not answer it here’s a terrifying google search for any teacher who is interested in having their students do some independent research on climate change. Google: “global warming raw data“.

Untitled

So the first result is a good one. A legit one. There are lots of links to reputable sites maintained by reputable scientists. Then the second result is a yahoo! answers post. The the third (third!) google result for a simple query on raw data turns up World Net Daily, a website for conspiracy theorists and people that think they’re going to be put in FEMA camps any day now. That is not a reputable site. They provide the opposite of “raw data”.

This is not a post about the messy politics and confusion-campaigns around climate change. But this does point to a particular difficulty that you’d hope would be much simpler: where can we find raw temperature data that we can actually use? For the record, a google search of “raw temperature data” yields much more acceptable initial results. But still, many of those results can be extremely difficult for a secondary math or science teacher to pick up and use, let alone students. For one, climate data is often presented in a file format that requires heavy coding knowledge or special programs to process (such as NetCDF). Second, it’s hard to know where to start with temperature data. Do you start by geographic location? Do you take the annual mean across the globe? How would one do that, exactly?

So this is the problem, and maybe a fundamental problem of teaching science: data are messy. We have to rely on others to package it for us. Scientists are interested in providing the raw data because they want people to have access to true observations, but that raw data is so vast and difficult to process (but not that difficult to interpret!) you have to get at least a Master’s degree before you can even start to decipher it. And often, scientists aren’t interested in culling the data to make it more digestible for the public. They’d prefer to show you the graph. This is great for communication, but not great for independent research. And worse, they’re now fighting on the same plane as disingenuous charlatans who are paid to be as such. So let’s provide students of science the raw data in a way that anyone with Microsoft Excel and a genuine curiosity can begin to explore the very real phenomenon of climate change.

My favorite site that does that is this NASA’s GISS Surface Temperature Analysis. In terms of accurate, raw, commentary-free, accessible, customizable, and processable data, I haven’t found a better place to start. Bookmark that site. Tell your students to go to that site. Start locally.

To find specific historic local weather stations, Katie recommends using the map rather than the search function. The map appears to have better functionality. So click on your favorite vacation spot and go find that precious, precious raw data.

Untitled

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Once you have the ASCII data (shown here), it’s simply a matter of copying and pasting it into Excel, or if you’re incredibly ambitious (or teaching a Stats class perhaps), having students import it into R, one of the industry standards.

For the uninitiated, let me translate a few things: 

D-J-F= December-January-February average

M-A-M=March-April-May average

J-J-A, S-O-N = I think you get the idea….

The last column, metANN = annual mean temperature. This actually might be the best first place to start. 

Berkley also has a nice data set organized by country. However, the accessible to-layperson data is a bit more hidden.

Untitled

If you’re not careful, you’ll end up downloading intense, non-accessible-to-the-layperson, NetCDF data. Which, again, is fantastic data, but difficult to work with yourself.

But now we’ve got two sites with data that can be tossed into Excel, R, or even those statistics packages designed for secondary students. Now that we have that data, we can do a lot with it.

Suggested Activities

  • Have students investigate the temperature trend in their area.
  • Create a linear model that predicts temperature as a function of year locally.
  • Assign each group or student a different region of the world to investigate and develop a linear model for.
  • Or what about this: develop a sinusoidal equation that describes monthly temperature. Get some trig in there.
  • Ask the question: is our town/state/country/planet heating up or not? Or is it too uncertain to tell?
  • Can you find local stations that DON’T show a warming trend? Katie suggests looking at weather stations closer to the poles to consider the potential impact of polar temperature trends. This might be a bit science-y, but it’s something I’d happily let students explore in a math class.

Once you have actual data, you can start to test it to assess that last, fundamental question (which then spurs thousands of other questions, like “should I have children?”). Is ß>0 under the general linear model? Once we have that answer, even if it’s just locally, we can start to talk about the implications.

Posted in projects, statistics | 6 Comments

Taxonomy of Problems (Part 2): Ways and what to assess

In my last post, I tossed out a loose taxonomy to name four different types of problems:

  • Content Learning Problems
  • Exploratory Problems
  • Conceptual Understanding Problems
  • Assessment Problems

I felt it necessary for myself. Up until now, I’d been labeling all problem equally: they’re problems! They’re tasks that are supposed to get students to learn stuff! But that implies a one-size-fits-all-ness that I don’t think is practical. The planning, time frame, facilitation, scaffolding, and – for our purposes in this post – assessment and wrap-up all look different, even if the task itself doesn’t look that different (after all, ideally we’re all using nonroutine problems with a low bar and a high ceiling regardless of whether it’s being used for formatively assessing student understanding or creating new knowledge).

It’s tough to throw out exact examples for assessment since we’re all working from different standards and tools. So I’m going to restrict it to the following universe of things to assess problems on: New Tech Network’s (where I work) most common Schoolwide Learning Outcomes (SWLOs) and the Common Core Standards of Mathematical Practice.

things to assess

Now, different teachers and different schools I’ve worked with utilize these different halmarks differently. In fact, many schools have difficulty even defining many of these indicators of student learning, let alone assessing. But nevertheless, we’re trying to get a general look and feel to what a problem rubric would look like, depending on what you’re actually trying to accomplish from said problem. We’re talking broad-brush here.

Content Learning Problems

Things to assess: Oral Communication, Professionalism/Work Ethic, Make sense of problems and persevere in solving them, Look for and make use of structure, Look for and express regularity in repeated reasoning

This might just be personal preference, but I’d be wary of assessing content knowledge in a learning opportunity for a student. If we are distinguishing between learning and confirmation problems, we might want to more rigorously assess content on the latter. Another one of my favorite wrap-up activities is this quick check-up as an exit ticket.

Exploratory Problems

Things to assess: Critical Thinking, Oral Communication, Collaboration, Model with Mathematics, Construct viable arguments and critique the reasoning of others, Use appropriate tools strategically

Assuming that the time-frame is a bit longer for an exploratory problem, and that the solutions and solution routes are varying, the wrap-up could consist of a formal presentation, followed by panel-style questioning.

Conceptual Understanding Problems

Things to assess: Critical Thinking, Collaboration, Written Communication, Reason abstractly and quantitatively, Construct viable arguments and critique the reasoning of others, Look for and make use of structure, Look for and express regularity in repeated reasoning

Here, I think it makes sense to have students reflect on and communicate what they’ve learned.

Assessment Problems

Things to assess: Critical Thinking, Written Communication, Reason abstractly and quantitatively, Use appropriate tools strategically, Attend to precision

In this case, one can easily envision a rubric that assesses the items above. Assuming these tasks are a bit more individualized, a written piece – almost like the free response section of an AP exam – might make sense. I’ll leave it up to the reader’s discretion whether or not to allot numerical point values.

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With these self-recommendations in hand, we can more easily (hopefully!) pick and chose what would go in a rubric and where, if a rubric is one of the tools in your toolbox.

Again, the idea is to make things easier, not more complex. And to better target outcomes for each and every problem. From these recommendations we might be able to construct a loose, lean problem planning template that is directly tied to the indicators you’re trying to peg with a particular problem. Maybe even some planned facilitation and scaffolding moves as well.

Posted in assessment, problem based learning | 2 Comments