Happy 2014 everyone! I hope your semesters are off to a good start. I started this semester going over some formulas with my Algebra 1 classes, specifically Pythagorean theorem and the distance formula. Last year, I introduced these formulas merely as plug and chug. This year, I wanted my kids to know why the formulas work, and how formulas are related. Even though many students had seen the distance formula in previous classes, they did not know how much it resembles the Pythagorean theorem (neither did I until two weeks ago). I found this resource that allows students to transition from the Pythagorean theorem to the distance formula in the coordinate plane.