"The protractor and the Bunsen burner. Playing the recorder in music class. Drawing arcs and circles with a compass in geometry. These tools of the education trade become part of our lives for a semester or two and then we move on."

"Today, NPR Ed begins a new series examining these icons of the classroom. We start off with a device that once was essential to higher-level math, in school and in the workplace, but now has all but disappeared:

The slide rule."

"'Take your batteries out,' Jim Hus says, watching his pre-calculus students remove the AA batteries that power their calculators. 'Let's do those multiplication problems again.'"