Field trips were easily the best part of school—whether it was a museum visit or a day at an amusement park, nothing beat the excitement of escaping the classroom. But let’s be real, none of my school trips ever included a surprise royal guest.

Kate, the Princess of Wales, went back to school Tuesday, joining a group of young students on a field trip. The 43-year-old princess, a mother of three herself, surprised visitors outside the National Portrait Gallery in London when she stepped off a bus with a group of 4 and 5-year-old students from All Souls CE Primary School.

Kate Middleton made an official visit to the National Portrait Gallery today and arrived in a different kind of style. Instead of the usual convoy of royal vehicles, the Princess instead emerged from a bus alongside school children as they excitedly made their way to view a new project in the gallery.

The Princess of Wales introduced a new phase in her early years campaign at the National Portrait Gallery in London