OLS -- Manually!!
An app designed for students to experience minimizing the sum of squared residuals by adjusting slope and intercept. Ideal for classroom use. It's fun, it's interactive, it's engaging! Compare the total sum of squares with how much you are able to reduce the unexplained variance, and feel accomplished! Make it a competition among participants! Who is able to reduce the sum of squared residuals the most? Maybe the winner gets a prize!? (Then, party's over -- time for some straight talk about strategies for solving convex problems like these. Adjust each parameter to a minimum one at a time until you find the global minimum.)
Submitted from Denver (mountain time!).