(CNN) Former first lady Michelle Obama went to her prom in a polka-dotted dress. We know that because she shared the photo Tuesday as part of a challenge to encourage students to vote.

"Throwing it back to my 1982 prom night and this pink satin, polka-dotted dress," Obama tweeted on Tuesday. "Join the #PromChallenge with When We All Vote and MTV and tell us what your school is doing to register students to vote. You could get a free prom for your school! "

Throwing it back to my 1982 prom night and this pink satin, polka-dotted dress.



Join the #PromChallenge with @WhenWeAllVote and @MTV and tell us what your school is doing to register students to vote. You could get a free prom for your school! Learn more: https://t.co/ggVjRpS3CU pic.twitter.com/x5lP0LHOUf — Michelle Obama (@MichelleObama) February 18, 2020

Obama, who co-chairs When We All Vote, partnered up with the non-profit and MTV's +1thevote campaign for the Prom Challenge, a program created to "celebrate and recognize 20 high schools across the country integrating voter registration into their schools in the most creative and impactful ways."

Students with ideas on how they can inspire their classmates to vote have until March 13 to submit their applications and authorization forms. The 20 winners will receive up to $5,000 for their school's prom.

Other celebrities fashionably joined Obama's efforts to encourage students to register to vote.

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