The duke and duchess took part in their video call with pupils and teachers at Casterton Primary Academy, which is near Burnley General Hospital.
The school has remained open to allow the children of key workers and other vulnerable students to continue attending school amid the nationwide lockdown.
With Easter just a few days away, some of the children wore bunny ears during their conversations with the royal couple, while others displayed illustrations they drew of their parents, some of whom work for the NHS.
“To you and everyone who is in during this time, it must be such a relief for all the parents who are key workers to know that their children have the normality and structure and they’ve got a safe place for them to be,” Kate told the children and staff members.
“So really, really well done and for all of you, I know it’s not easy circumstances, but it’s fantastic.”
One teacher responded: “Thank you so much. I think everyone is just pleased to be able to help.”
Prince William then added: “Good northern volunteering spirit going on up there, very good of you!”
At one point, one of the children asked the duke what name he would wish to go by, considering “the first William was William the Conqueror”.
The 37-year-old laughed off the question, stating: “I don’t think I can answer that.”
When the pupils appeared on the video wearing bunny ears for Easter, Kate said: “We should have had our bunny ears on!”, while Prince William stated: “That’s a strong look.”
One pupil, a 10-year-old called Harris, showed the royal couple a picture he made of his mother, who is part of the NHS workforce.
“This is a picture of my mum and she works for the NHS as an admin for the health visitors and I’m really proud of her,” Harris said.
“Well done you! Can you hold it up a bit to your left so we can see it — that’s it, brilliant!” Prince William said in response. “Look at that, that’s a great picture, well done.”
“Well done, it’s brilliant,” Kate added. “I agree you should be very proud of her, they’re doing an amazing job all the NHS workers, so well done you.”
When the Duke of Cambridge asked Harris and another student called Lloyd how they felt about being in school, they said they felt “happy”.
The couple met 18 children in total throughout their virtual visit, who were rotated in small groups in front of the camera in order to adhere by social distancing guidelines.
Anita Ghidotti, chief executive of the Trust, spoke about the children’s reaction to meeting Kate and Prince William.
“They couldn’t believe it. It was just absolutely fantastic,” she said.