The “Jeopardy”-style answer is: The pop-up camper, the shopping cart, and the wheelchair brake system.

The question: What are common products that were first introduced at the Minnesota Inventors Congress?

For 50 years inventors from across the country have been flocking to Redwood Falls, Minn., to display their wares at the MIC, the world's oldest invention convention.

“It gives inventors a place to test-market their products,” says Deb Hess, executive director of the nonprofit association and planner of the annual convention. She generally gets between 50 and 200 exhibitors — that is, inventors — who come to show off their handiwork. The three-day event usually attracts more than 2,000 attendees.

What started 50 years ago as a way to bring new products and manufacturing to the area has grown into one of the most prestigious events in the country for inventors — it was even featured on “The Tonight Show with Jay Leno” last year.

Other inventions introduced at the MIC over the years include The Gripper, which is used to tie down boats; the quad-cane, a four-pronged cane; the Bedfan, a cooling system that attaches to the bed; and an ice-fishing vehicle (see photo). For more information on the 50th anniversary event next June, go to www.inventhelper.org.