The First Lady of the United States Thursday called on developed countries to promote a cultural change in gender perceptions during her visit to the Spanish capital, Madrid.

Michelle Obama spoke before 600 college and high school students, urging them to make an effort and contribute to this cultural shift towards gender equality, which would be achieved not only through legislation but by "changing hearts and minds."

"Every one of us has the power and obligation to be a champion for girls around the world," Obama said.

The First Lady, or FLOTUS as she is known to White House staff, who greeted the audience with an effusive "Hola!" ("hello" in Spanish), arrived Wednesday in Madrid accompanied by her daughters, Malia and Sasha, as well as her mother, Marian Robinson.

Madrid is the last leg in a trip that included stops in Liberia and Morocco, as part of her international "Let Girls Learn" campaign.

In this campaign, Obama talked to girls and teenagers facing daily challenges to their right to learn, ranging from long walks to school to sexual harassment, as well as being compelled to abandon their studies due to marriage when they actually want to continue their education, since they "want a better future."

According to Obama, these young women's difficult situations are caused not only by a "lack of resources," but often stem from prejudice and cultural beliefs that consider women "second-class citizens" and only place value on their bodies, reproductive function or subservient and often sexist work roles instead of their intrinsic human dignity.

Obama shared her own life story with the girls in the audience, reminiscing of the hurdles faced by a woman raised in a working-class black family in Chicago's South Side, who had to fight against ubiquitous prejudice to graduate from college and succeed professionally.

Spanish Queen Letizia also attended the speech, telling the audience after Obama had spoken to join in the "thrilling" task of promoting women's education around the world.

Education "transforms and protects" girls' future, and is linked to "social justice and democracy, family welfare, the promotion of equality and improved health and nutrition," the queen said.

After the event, Queen Letizia and Michelle Obama went on to the Zarzuela Royal Palace _ the Spanish royal family's official residence _ for a private talk.