Kate is learning new things during her trip in America.

On Friday, Catherine, Princess of Wales headed to Harvard University outside of Boston, Massachusetts, where she visited the Center on the Developing Child. It was a solo outing for the mother of three, who is on a three-day visit to the United States with her husband, Prince William.

The 40-year-old spoke with researchers about the advances in science to ensure a promising future for children. The British royal, who is an advocate of early childhood development, was spotted taking notes.

Kate Middleton's signature

The signature of Britain’s Catherine, Princess of Wales and the signature of her father-in-law, King Charles III from his 1986 visit are seen as she visits Harvard University on December 2, 2022, in Cambridge, Massachusetts.  (Photo by Paul Edwards-Pool/Getty Images)

Middleton’s father-in-law, King Charles III, visited Harvard University in 1986. She signed the guestbook 36 years later.

PRINCE WILLIAM, KATE MIDDLETON APPEAR IN NEW PHOTOS TAKEN DURING REHEARSALS AMID ROCKY START TO US TRIP

Kate Middleton visiting Harvard

Britain’s Catherine, Princess of Wales visits the Center on the Developing Child at Harvard University as part of her ongoing work to elevate the importance of the early years to lifelong outcomes, on December 2, 2022, in Cambridge, Massachusetts. (Photo by Paul Edwards-Pool/Getty Images)

The Harvard Center has supported The Royal Foundation and, more recently, The Royal Foundation Centre for Early Childhood. That foundation, which the princess launched last year, focuses on research into the early years of childhood. It aims to "raise awareness of why the first five years of life are just so important to our future life outcomes, and what we can do as a society to embrace this golden opportunity to create a happier, more mentally healthy, more nurturing society."

Last week, Middleton wrote an op-ed that was published by The Telegraph. She described how society must do "everything we can to nurture our children."

"Over the past 10 years, talking to a wide range of experts about how we deal with societal issues, like poor mental and physical health, I have become more and more sure of one thing: if we are going to create a healthier and happier society for future generations, we must start by understanding and acknowledging the unique importance of the first five years of life," she wrote.

William will also have his own solo engagement. The 40-year-old will tour the John F. Kennedy Presidential Library and Museum.

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Kate Middleton holding her purse while visiting Harvard University

During their trip, which will last for three days, the royal couple will learn about the environmental challenges Boston faces as well as meeting those who are combating the effects of climate change in the area.  (Photo by Paul Edwards-Pool/Getty Images)

The Prince and Princess of Wales traveled to Boston on Wednesday for three days of engagements. It is their first trip to the U.S. in eight years.

Boston, the birthplace of John F. Kennedy, was chosen to host the second annual prize ceremony because of the late president’s 1962 "moonshot" speech that setting the challenge for Americans to reach the moon by the end of the 1960s. It inspired the prince and his partners to set a similar goal for finding solutions to climate change and other environmental problems by 2030.

MEGHAN MARKLE AND PRINCE HARRY JOCKEY FOR ATTENTION AS PRINCE WILLIAM, KATE MIDDLETON MAKE HISTORY IN US

Prizes will be awarded by Rami Malek, Catherine O’Hara and Shailene Woodley. The event will also feature performances by Billie Eilish, Annie Lennox, Chloe x Halle and Ellie Goulding, who performed at the couple’s 2011 wedding reception. The show will highlight packages voiced by Sir David Attenborough and Cate Blanchett, who is an Earthshot Prize Council member.

The Associated Press contributed to this report.