Curvefitting With Geogebra

squash curve 1Inspired by some of my own forays into curvefitting with Geogebra (the squash at the right, or my Sine Waves on the Beach), I’ve created a student project built around the idea.

Finishing up a unit on trigonometry with graphs of trigonometric functions, it occurred to me that I have never really been comfortable teaching transformations.  I think part of the reason is that it’s hard to get your hands dirty, play around, and develop intuition with this topic.  This is where Geogebra comes in!

The project essentially works like this:

1)  Students find an image, preferably one they capture themselves

2)  Students paste the image into Geogebra

3)  Students graph a relevant trigonometric function and play around with the various parameters (like period, amplitude, phase shift) until the curve fits the image

4)  Students can use domain restrictions, and some of Geogebra’s aesthetic features, to polish everything up.

The first run of this project has produced some great results!  You can see some sample student work here, and more on my Facebook page.

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Library of Visual Manipulatives

algebra tilesThis is another terrific resource:  the Library of Visual Manipulatives from Utah State University.

http://nlvm.usu.edu/

There are one hundred or so simple, interactive programs available spanning Algebra, Geometry, Numbers and Operations, Measurement, and Data.  And everything is sorted by appropriate age level.  There are certainly a  lot of interesting activities to navigate through here.

I’d say this is NSF money well-spent.

Toothpick Sequences

toothpick sequenceThis is a cool applet that allows you to explore various fractal “toothpick sequences”:

http://www2.research.att.com/~david/oeis/toothpick.html

A number of options allow the user to look at variants of the object, zoom in, change iteration parameters, and change the underlying sequence.  Click the Introduction button for a short overview.

Not sure what ATT Research plans to do with this, but it’s fun to play around with!

Art and Math Blog

buckyball fieldThis is a mind-blowing set of math/art projects by Daniel Walsh.

http://danielwalsh.tumblr.com/

At the right is a visualization of the magnetic field created by a small triangle of buckyball magnets.

There are only a few posts here, but they are fascinating and stunningly beautiful.  I hope there are more coming!

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Math Lesson: NCAA Rankings

ncaa trophyMy latest contribution to the NYT Learning Network is a mathematics lesson build around the way NCAA basketball teams are ranked.

http://learning.blogs.nytimes.com/2011/03/14/whos-no-1e-investigating-the-mathematics-of-rankings/

Quantitative rankings are ubiquitous these days, and they are playing an ever-increasing role in teaching.  Colleges have been “ranked” by publications for years, but now public schools are being assigned grades and even teachers can be ranked according to complicated, and often controversial, formulas.

In this lesson, students are tasked with creating their own rankings of the sports teams.

Looking only at winning percentage, therefore, may not be a fair assessment of who is better than whom: if Team X plays in a relatively weak conference, and Team Y plays in a relatively strong conference, it will be easier for Team X to record wins. This is similar to the idea of ranking students based on unweighted G.P.A.’s: such a system may well reward students who take relatively easy classes and put students with more challenging programs at a disadvantage.

So, student pairs should explore approaches to addressing this issue by attempting to quantify a team’s strength of schedule, thereby creating a ranking system that will take into consideration the quality of each team’s opponents.

These rankings only make as much sense as the underlying mathematics.  Hopefully, through investigating the way the NCAA ranks basketball teams, teachers and students can learn to deconstruct these ranking systems and better evaluate their utility .

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