This is an application take from the MathBits web site. Instructions for TI calculators are at the bottom. Full lesson.
The points were type in a spreadsheet (A,B).

Use Move Tool move and your mouse to highlight the data in the spreadsheet on the right.

Right-click on the highlighted area and select Create|List of points. You now have the data graphed.

Use to Line Tool to manually draw a line of best fit.

From this line you can find the slope of the line using the Slope Tool and click on the line.

Use the Intersection Tool to find the y-intercept, right-click on point to show point and value. To look get the y-intercept, right-click on the point, select Object Properties and change the label option to name and value.

Write the equation of the line, y = slope x + y-intercept.

Enter your equation for y = mx + b here:

To validate your solution, clear the applet with recycle recycle, repeat Step 1 and Step 2 followed by Step 9

To check your manually drawn line, use the line of best fit tool bestFit to validate your solution.

Click on Find f(x) button, compare result above to the f(x) on the GeoGebra screen.

To check you equation, enter the points into a TI Graphing calculator using the instructions on the MathBits website. Use the linear reqression tool to find the linear equation and type this equation into the input bar to verify the correlation.
Enter the points on a TI Graphing calculator. Use the linear reqression tool to find the linear equation and type this equation into the input bar to verify the correlation.

Mathbits http://mathbits.com/Mathbits/TISection/Statistics2/linearREAL.htm
y = 3.244x + 26.012
This applet can be used by teachers in a demonstration mode in the classroom or teachers can have students load it on their own computers as a worksheet to be completed for a grade.