Learning Curve

1930: Overhead Projector.

Marketplace Contributor May 14, 2014

It got its start pre-WWII, when the Army used it for training soliders. Then, the police got interested, because it made identifying suspects easier. You could project images across a screen. By the late 1950s and early 1960s, overhead projectors made it into schools, and the interactive classroom was born.

Teachers liked them because they could use pre-printed transparencies for lessons, and enlarge them easily. No more need to write everything in extra-large on the blackboard. In most classrooms computers have taken their place. 

We’re here to help you navigate this changed world and economy.

Our mission at Marketplace is to raise the economic intelligence of the country. It’s a tough task, but it’s never been more important.

In the past year, we’ve seen record unemployment, stimulus bills, and reddit users influencing the stock market. Marketplace helps you understand it all, will fact-based, approachable, and unbiased reporting.

Generous support from listeners and readers is what powers our nonprofit news—and your donation today will help provide this essential service. For just $5/month, you can sustain independent journalism that keeps you and thousands of others informed.