This screencast (hopefully) covers the basics of parabolas: focus, vertex, directrix, and the standard form of an equation of a parabola. Why do we ask students to spend so much time on these things? Because math teachers are by and large cruel and cynical adults who enjoy inflicting mental anguish on adolescents. Not!
Actually, parabolas are very important because they model so many things in life – not the least of which is projectile motion. The next time you quench your thirst at a water fountain, take a look at the stream of water: yes, that’s a parabola. If you look at a cross section of a satellite dish, you’re looking at a parabola. If you take a flashlight apart, and look at the reflective bowl surrounding the light bulb, that’s a parabola. Parabolic collectors are used to enhance the sensitivity of microphones.
Parabolas are everywhere – fortunately, they are completely harmless.
