University of Georgia
University of Georgia: Slope of Lines
This site provides a detailed unit on finding the slope of lines that investigates methods for solving systems of equations. Good lesson plan for class.
Texas Education Agency
Texas Gateway: Tea Statistics: The Regression Equation
A tutorial on how to find the line of best fit or least-squares regression line for a set of data in a scatter plot using different methods and calculations.
OpenStax
Open Stax: Graphical Analysis of One Dimensional Motion
In the following interactive module students will describe a straight-line graph in terms of its slope and y-intercept. They will determine average velocity or instantaneous velocity from a graph of position vs. time.
Other
Ctte: Geometer's Sketch Pad Activities
This site offers numerous activities for middle school and high school students to explore using Geometer's Sketch Pad.