dy/dan

So Happy Together #3

January 31st, 2008 by Dan Meyer

Make the marriage of your digital projector and laptop a happy one.

One Idea:

Become the teacher/learner hybrid.

Like this:

I buy some tea from the deli next to the school. $1.80. I'm at the grocery store the next day and notice a box of the same tea for $6.49. 18 bags. I start wondering, "how much is the deli profiting off our transaction?"

Then:

I take a picture of the box and put it in front of my beginning algebra classes the next day — today.

This is how we introduce rates: how it doesn't just matter that the box costs more or that you get more tea in it rather you must consider the two things against each other.

After we divide price by bags and come up with 36 cents per bag, the students notice that same figure on the price tag. The grocery store helpfully makes these calculations for you.

So when I put up two more photos, two sports drinks, one in bulk, the other in miniature six-pack, I censor those figures¹.

And we spend 45 minutes running computations, discussing the results, arguing over the significance of the results — all from three photos.

No wipes, checkerboards, animations, or other PowerPoint detritus. This is the 21^st-century digital projector bashed back into the 20^th century.

This is one of those carousel slide projectors I'll only pretend to have seen in person. I'm only projecting still images but here, in the 21^st century, I can draw those images from infinite sources from around the globe or my local supermarket.

This practice habituates like a hard drug. With a digital projector waiting back in my classroom, I can't help looking for interesting, relevant images to put in front of my class.

A digital projector shrinks the time-gap between my learning moment and theirs.

A digital projector has effectively buried the difference between What Fascinates Me and What I Teach.

Previous Editions:

So Happy Together #1: Easy, permanent storage of cool material.
So Happy Together #2: Visualize and enliven perfunctory classroom business.

In this particularly mind-blowing example, the cost per ounce was the same. [back]

16 Comments »

16 Responses to “So Happy Together #3”

on 01 Feb 2008 at 4:44 am1 Tim

Thanks for the incredibly easy way to use a projector in class. I will be sharing this with the teachers on my campus to show them just how easy all this digital stuff can be!
on 01 Feb 2008 at 6:26 am2 Lynne Bailey

Beautifully simple and well worth sharing.. thanks! I love seeing everyday math in the classroom.
on 01 Feb 2008 at 11:55 am3 Benjamin Baxter

Totally defeats the “how is this going to help me?” argument so many math teachers have trouble with.
on 01 Feb 2008 at 2:07 pm4 Penelope Millar

Ben – and makes this history teacher jealous. What a way to convince them that math actually is everywhere!
on 01 Feb 2008 at 4:28 pm5 Nick Pernisco

This is so great because kids will learn from real world examples using money. I remember being terrible at math as a kid, except for the times the teacher put dollar signs in front of the numbers… then I was her best student. What a difference a small change in perspective makes.
on 02 Feb 2008 at 7:46 am6 Math Stories : Real World & Cognitive Dissonance

[...] I’m becoming more and more convinced that if we want to use real world examples, they better be completely real, with realia to back up the premise. If we are going to create fictional problems to emphasize [...]
on 02 Feb 2008 at 8:18 am7 jose

Yeah, this is good. I would most definitely mod this for my classroom.
on 04 Feb 2008 at 1:04 pm8 Instructify » Blog Archive » Rethink the Way You Use Your Digital Projector

[...] Dan Meyer at dy/dan reminds you that you don’t have to create a multimedia extravaganza to incorporate technology [...]
on 08 Feb 2008 at 4:49 am9 Kate

Great use of digital photos to introduce rate. I tried a similar thing this year. My problem is steering the discussion to an understanding that “rate” is a way of saying “how much for one”, and then tying that to “slope” represents how much the graph goes up every time you go over by one. I feel like there is not much help or training available to develop that skill as a teacher.
on 10 Feb 2008 at 7:10 pm10 sam shah

http://consumerist.com/354024/kfc-is-sneaking-extra-profit-from-bigger-orders

This particular per-unit pricing might interest your kids too!
on 22 Feb 2008 at 12:27 pm11 Carnival of Mathematics 1000 « JD2718

[...] is convinced that teaching is better with digital/2.0/power point – and here he shows off how he introduces “rates” – it’s a reasonable guess that no chalk was harmed during that lesson. 22 – Dave Marain has a [...]
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