Searching for Math

I just recently took a course at the University of Nebraska Lincoln called Math in the City.  It is a problem based course where our group looked at stock analysis and Modern Portfolio Theory.  It started out slow, but at the end of the course everything fell together.  What I gleaned from the course that can very useful for high school students in the teaching of spread and central tendency was a fabulous, easily approachable way to intelligently compare stocks using Google docs spreadsheets.

There is a set of code in Google docs that can be used to retrieve daily data from the New York Stock Exchange.  Type this set of code into the first cell of your Google spreadsheet. =googlefinance(“Stock Symbol”, “type of Data”, “Beginning Date”, “Ending Date”) For example, in the photo below, I set up the formula to read Disney’s closing price from 5/10/2007 to 5/9/2012.  The spreadsheet then displays all closing bell prices for Disney between and including those dates.  With this data it is then possible to generate the daily rate of growth for that stock.  Using the same rate of change formula I teach to eighth graders which is Rate of growth =(new – original)/original.  In the photo above I used = if(b5<>”",(b5-b4)/b4,”") Thanks Jerel.  Then you find the mean of this daily return rate along with the variance (which represents the risk of the stock) and plot these two numbers on an x-y scatter where return rate is the y – axis and variance is the x-axis.   The graph with stock data is plotted below and right.  For example it would be easy to see in this graphic that IBM has a high positive return with low risk, while XIDE has a negative return with a high risk based on five years of data.  (This is for educational purposes only, and is not intended as investment advice.) Here is the actual spreadsheet Just change the symbols in each sheet and the dates.

https://docs.google.com/spreadsheet/ccc?key=0Apxer8IfY7S7dGExeDdrUFhNM3BZMXRfWnNnSXlvbGc

In the course we went into more detail about the efficient frontier, and comparing stock portfolios where we calculated the rate of investment for each stock to maximize return and minimize risk, but this just seamed like an easily accessible application for almost every student I teach in 10th – 12th grade.  You can only look at the document right now.  As soon as I figure out how to protect all the math stuff I will allow anyone to enter the stocks they want to analyze.

The problem – We have a field that currently uses gravity fed irrigation (the lighter colored field in the center of the picture).  This mode of irrigation is very wasteful, and so a more efficient center pivot irrigation system needs to be put in place.  Design a center pivot irrigation system for the field below.  Your design must utilize exactly the amount of irrigated acres available.  Additional irrigated acres are not allowed and utilizing less than is currently there will loose you money!!

Once the designs are completed we will do a cost analysis of their designs.  Prices to consider.  Each Center pivot costs approximately $50,000.  Running electricity and water pipe from the well to the center point $7.00 per linear foot.

Transferring dry land to irrigated acres costs $50 per acre.   Transferring pasture to irrigated costs $500 per acre.

Consultant fee for asking the teacher a math related question- $1,000 per question answered. (an idea to make it more lifelike).

When we are done with this project I will post some of their plans after Christmas.

In this silent video I show how a group of Ag and math students estimate slope in order to calculate how erodible the newly planted field will be.   I just wanted the video up fast.  I will spend some more time later refining it and adding some other explanations.

A major question I had as a math teacher, after hearing this is how the Ag class estimates slope at a range management competition.

How is it possible to use the hypotenuse to calculate a fairly accurate estimate?

Estimating Slope Take One [ 2:28 ] Play Now | Play in Popup | Download