KIRSTY WIGGLESWORTH/POOL/AFP via Getty Images Kate Middleton

Kate Middleton is back in class as she takes the next steps in her work on behalf of young children.

The Duchess of Cambridge, 39, headed to a school in London on Wednesday to visit with students learning about neuroscience and the importance of early childhood development on the brain.

During the outing, the mom of three joined a science lesson at Nower Hill High School. The lessons were built on research from Oxford University's department of psychiatry about the importance of learning how the first five years of children's lives impact their entire life.

"Really well done," Kate told the students. "I completely found it interesting. It's a real passion of mine," she said. "Learning about babies' brains, about how our adult brains develop and how our early childhood influences the adults we become."

She added, "Keep thinking about it, keep talking about it with your friends. Well done, I'm super impressed. Thank you for having me today."

Earlier this year, Kate launched the Royal Foundation Centre for Early Childhood, marking the latest significant step in her long-term mission to help kids and parents. The teaching project caught the eyes and ears of her foundation, and she wanted to see how it was being put into action in classes.

Kirsty Wigglesworth/AP/Shutterstock Kate Middleton

Louise Voden, the headteacher of the school, tells PEOPLE she was surprised that Kate actually joined in with the class. "I never thought she would do that!"

"She was an absolute natural. She was really interested in what they had to say and their thoughts about the materials they had been learning about," Voden adds. "She clearly feels very passionately about it."

The children, who were ages 12 and 13, didn't know until about 15 minutes before the royal entered the classroom that she was coming.

As Kate walked down the hall, children from other classrooms got out of their seats in excitement. Voden told Kate they had asked the students not to do that, but she was relaxed and waved back and said hello. "It was all delightful," Voden says.

KIRSTY WIGGLESWORTH/POOL/AFP via Getty Images Kate Middleton

She "made them feel at ease" by "reading the children's body language and knowing who is perhaps a little hesitant and nervous," Voden tells PEOPLE. "She picked up on the signs with the children, and got down to their level and asked questions in language they can understand. She really engaged with them and asked them great questions.

"She was just extremely down to earth."

Referring to Kate's ongoing work on behalf of kids' mental health, Voden adds, "You can see the interest genuinely stems from the fact that some children who don't enjoy the right experiences in their very early years go on to have real problems. She is really keen to see this work go into the mainstream science curriculum.

"Speaking with her she is clearly interested in young people's mental health and is concerned about young people's mental health. Things have gotten so much worse for young people during the pandemic. We are seeing poorer mental health in young people at the moment and it is something we are all concerned about."

KIRSTY WIGGLESWORTH/POOL/AFP via Getty Images Kate Middleton

Much of Kate's public work over the past 10 years has been focused on how challenges such as addiction, family breakdown, poor mental health, suicide and homelessness can be rooted in the earliest years of someone's life. At the end of the visit, Kate told the class she was "super-impressed" with the knowledge in the room and praised them for their work.

RELATED: Kate Middleton and Dr. Jill Biden Meet Local Children — and Feed Rabbits! — During Afternoon Outing

KIRSTY WIGGLESWORTH/POOL/AFP via Getty Images Kate Middleton

The researchers, led by Louise Dalton, Consultant Clinical Psychologist, and Elizabeth Rapa, Senior Post Doctoral Researcher at Oxford University's SEEN project, found that the lessons gave the students valuable tools that will help them as they interact with younger siblings, become parents one day or begin careers in the care sector.

Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

Kirsty Wigglesworth/AP/Shutterstock Kate Middleton

Kate's long-term commitment in the area of early childhood development was cemented when she started the Royal Foundation Centre for Early Childhood, which she and her staff hope will increase awareness of and action on the extraordinary impact of the early years.

"The Duchess has made the observation that the more you learn about the science of early childhood, whether it's brain development, social science, what it means for our adult mental health, the more you realize that this is the social equivalent to climate change," a royal aide said over the summer. "But it is not discussed with the same seriousness or strategic intent that that issue is."