US First Lady Michelle Obama took afternoon tea with Prince Harry at Kensington Palace today.
Mrs Obama is in Britain to discuss her campaigns for girls' education and support for military families.
She is a promoting the Let Girls Learn initiative, championed by her husband, US president Barack Obama.
The campaign is billed as "working together to open the doors of education for girls around the world".
Earlier, Mrs Obama, her daughters, Malia, 16, and 14-year-old Sasha and her mother, Marian Robinson, took tea with Prince Harry at Kensington Palace.
The three generations of the Obama family spent around 40 minutes chatting with the 30-year-old, who was keen to catch up with them after the warm welcome he received at the White House during his trip to America two years ago.
Kensington Palace said the Prince was "very pleased" to host Mrs Obama and "delighted" to meet her daughters and her mother, who is said to be known as Mrs R.
Before she made her visit to Prince Harry, the First Lady told a group of inner-city London school pupils "the world needs more girls like you".
Once the ear-splitting screaming and cheering had died down, students from the Mulberry School For Girls in the heart of the East End retook their seats and got the chance to question the US First Lady.
They heard Mrs Obama tell them that, as someone who is black, female and also comes from a working-class background, she understands the need for a good education.
She told a packed assembly at the school for pupils aged 11 to 18 that she understands the challenge of being "overlooked" and undervalued.
Mrs Obama said: "With an education from this amazing school you all have every chance you need to rise above the noise and fulfil every one of your dreams."
Despite facing Islamophobia and poverty, 83% of the students from the Tower Hamlets school, including many from ethnic minorities, manage to secure a place at university.
Mrs Obama said: "The world needs more girls like you to lead our parliaments, our boardrooms and our universities. We need you for tackling the problems of climate change, poverty and disadvantage."
Mrs Obama told the girls she could understand how it feels to be "lost in the shuffle" and that she never would have believed she would one day be the First Lady of the US.
She also told them it can be difficult to feel comfortable when people are saying things about your religion and you have to face those who need to "see beyond the headscarf".
During her visit to Mulberry School, Mrs Obama, who was earlier joined for a round-table discussion by International Development Secretary Justine Greening and Education Secretary Nicky Morgan, said the US and UK would join forces to try to improve access to education for girls internationally as globally there are around 62 million girls not in school.
Educating youngsters in the troubled Democratic Republic of Congo will be one of the focuses of this new multimillion-pound project.
Mrs Obama's advice to the girls in the packed hall was that the trials and tribulations they face could help to make them great.
She told them: "Resilience and the ability to overcome obstacles is success. Take those challenges you are facing and own them. With every challenge you overcome, you are becoming better.
"Don't just be book-smart, be smart about the world - know your community, know your politics.
"You have to be informed and engaged all the time - not just when you think it is interesting or cool. As young women we have to be interested in politics.
"You have to think about your whole education."
Mrs Obama also met with British Prime Minister David Cameron and his wife Samantha.
The First Lady embraced the pair as she posed for photographs outside Downing Street.
She was accompanied by her daughters and mother for the visit.
Writing in the Financial Times, she said girls face obstacles to education such as forced marriages, early pregnancies, abuse and sexism, and described it as "a heartbreaking injustice".
"That kind of life is unthinkable for the girls in our lives, so why would we accept this fate for any girl on this planet?" she wrote.
"This week I will join Prime Minister David Cameron in London to begin to answer that question, and announce a series of partnerships between the US and UK to educate adolescent girls in developing countries around the world."
She praised the UK as a "global leader" for girls' education, adding: "In addition, our development agencies and two of countries' leading universities will collaborate on evidence-based research to determine the best ways to educate adolescent girls. And British and American partners will work together to support teacher training, girls' leadership camps, and other community-based programmes in developing countries.
"Combined, these efforts total nearly 200 million dollars (£128 million) - but, given the scope of this challenge, even that is nowhere near sufficient. Girls' education is a global issue that requires a global solution."
After London, the party will fly on to Italy to meet US armed services families based in Europe and to visit the Milan Expo as part of the third strand of her work, encouraging healthier diets for children.