**Author** David Graser, Yavapai College, Prescott, AZ (David_Graser@yc.edu)

**Abstract**

This project originated from an extensive data set of college costs published by the College Board. I needed a first project for my college algebra class that incorporated the concepts surrounding a linear equation and slope. Although this project could be done with almost any type of technology, I required my students to use Excel as well as Mathtype to help them document their work. In this project, each student was given a state for which the average college cost in 2004-2005 and 2007-2008 was known for two year colleges, public four year colleges and private four year colleges. For each type of institution, the student finds the equation of a line through the two data points and predicts when the college costs will double.

- Content Area – College Algebra
- Time Frame – 2 Weeks with Mini Lectures
- Published – April 1, 2008
- Keywords – point-slope form, line, slope, data, linear, rate

**Project Content**

**Project Letter** (DOC | PDF)

**Project Data** (EXCEL | PDF)

**Scaffolding Resources**

**Technology Assignment 1** (DOC | PDF) This assignment is designed to get the students graphing their data points on their graphing calculator and in Excel.

**How To Graph Two Points on the TI-83** (Video)

**How To Graph Two Points in Excel** (Video)

**Technology Assignment 2** (DOC | PDF) In this assignment, students will solve an equation algebraically and graphically. This should prepare them determining when their college costs have doubled.

**Verify the Solution to an Equation Using the TI-83** (Video)

**Verify the Solution to an Equation Using Excel** (Video)

**Show How To Solve an Equation Using Mathtype** (Video)

** How to Find a Point of Intersection on a TI Graphing Calculator** (PDF) This document shows how to put in two equations and find the point of intersection using the intersect command from the CALC menu.

**How to Find a Point of Intersection in Excel** (PDF) This document shows how to find the point of intersection using GOAL SEEK in Excel.

**Notes**

- Some states have institutions whose average costs are decreasing. If you choose to have your students find when costs double, don’t choose one of those states.
- The second worksheet in the Excel file has the annual data for college costs from 2004 to 2008. You could make this into a modeling project or find the equation of a line through a different set of years.
- Students could compare one type of institution in two different states.