Ever since her husband's administration ended, Michelle Obama has pretty much stayed out of the spotlight. (You know, except for sharing the occasional squeal-inducing Valentine's Day post and the pictures of the family's dream vacation.) But on Thursday, the former first lady came back to social media to share a photo that references a darker time in America's history. The photo, taken at the Brown v. Board of Education National Historic Site in Topeka, KS, shows an unnamed white woman and Obama standing in front of two bathroom signs that read "White" and "Colored." In case you need a little history refresher, here's the deal with the Brown v. Board case: In 1951, a group of Black parents sued the Topeka Board of Education because their kids were denied admission in their neighborhood's schools and were forced to enroll in one of the four schools in the city for Black students. The case was named after Oliver Brown, a minister who was the first parent listed in the lawsuit. When the case reached the U.S. Supreme Court alongside similar cases from Delaware, the District of Columbia, South Carolina, and Virginia, the justices decided to consolidate these cases under one name, Oliver Brown et al. v. the Board of Education of Topeka. This would be the case that ended the racial segregation of schools in 1954. That's why Obama's post reads, "Remembering those who have made possible the dreams of today. Will never forget. Will never stop honoring their legacy. #BlackHistoryMonth"