Watch President Obama and Prime Minister David Cameron greet the schoolchildren in Welsh below:
Primary school children were given a lesson they are unlikely to forget as Barack Obama and David Cameron dropped in to class.
Youngsters were treated to a series of Nato-themed second day back at school.
Army reservist Lieutenant Rachel Broughton, 28, of Tenby, spoke to year five and six pupils about the summit and how Nato encourages co-operation between different nations.
Among the crowds gathered outside was college student Jay Singh, 16.
He said: "It's pretty surreal, Barack Obama being in Rogerstone. It's great that he's come here and shows Newport has plenty to offer and it's not just about Cardiff.
Earlier on, children had to go through a metal detector before starting their second day of the academic year.
When a smiling Mr Obama walked into a Year 6 class speaking Welsh, the pupils' nervous chatter turned to delighted smiles.
After listening to a question-and-answer session about Nato, Mr Obama and Mr Cameron were ushered into the school hall to inspect youngsters' artworks.
Sitting down at a low-level children's table, perched in front of a classroom display about adventurers such as US astronaut Neil Armstrong, they chatted with youngsters about their drawings of the summit venue, the Celtic Manor.
It's been a real pleasure to host Barack Obama and David Cameron. As you can see, the children have not stopped smiling. It's given them a tremendous sense of pride. We feel incredibly lucky to have been chosen for the visit. It's quite funny how it came about because in July we tweeted a picture to Nato's account with a drawing the children had done of the Nato logo asking for a VIP visit.