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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Paper Pyramids

Another installment from my Fun With Folding series:  paper pyramids!paper pyramid -- top

First, start with a triangular cut-out.  Construct this triangle’s medial triangle by connecting the midpoints of each side.  If you don’t have a ruler handy, just fold corner to corner, and crease in the middle to find the midpoint of each side!

Medial Triangle

Now, fold up the sides and tape them together!

paper pyramid -- side

The best part about this activity is that it doesn’t always work!  Finding out which triangles this will work for, and which it won’t, leads to lots of good mathematical questions to explore!

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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 .

12 Ways to Use the NYT to Develop Math Literacy

Here’s my latest contribution to the New York Times Learning Network:  a collection of ideas for math activities that are built around content from the New York Times.

http://learning.blogs.nytimes.com/2011/02/28/12-ways-to-use-the-times-to-develop-math-literacy/

The activities run the gamut of the paper, and include examples in Finance, Real Estate, Dining and Sports, among others.  Here’s an example:

1. Find Your Dream Home

How much would you pay for 1,000 square feet of living space inNew York City? What about Los Angeles? Use the Real Estatesection of The Times to compare and contrast the cost of housing in different parts of the country, or even different parts of the world.

Or find a home for sale in your area, find an up-to-date interest rate (for that, you might try ERate), and use the mortgage calculatorlocated next to the real estate listing to compute your monthly payment over the term of the loan. How much would you have to earn per year to afford your dream home? How long would it take to save up enough for your down payment?

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