David Beckham, Anne Marie and Jamie Oliver also helped read parts of the poem to mark the end of Mental Health Awareness week.
Kate has teamed up with The Book Fairies, an organisation that encourage people to pass books on for others to enjoy.
Mila Sneddon asked the duchess if she was wearing a costume when they spoke on the phone.
Kate said Louis loves his scooter and his bike in a call with a young girl recovering from cancer.
Kate spoke to Harriet Nayiga who has set up a community group which supports mothers in poverty.
Parenting expert Tanith Carey told Yahoo UK William and Kate have eschewed the royal protocol which Diana had to follow.
Princess Charlotte turns six on Sunday, while the boycott continues.
The video follows the release of two new portraits of the couple as they celebrate 10 years married.
Prince William and Kate are celebrating their 10th wedding anniversary on 29 April.
The couple have revisited a charity which benefitted from a royal donation back when they got married in April 2011.