Per The Sun, the Duchess of Cambridge urges her children—Prince George, 8, Princess Charlotte, 7, and Prince Louis, 3—to calm down when they act up by telling them, “Let's take a break.” However, if a full meltdown does happen in public, she removes them from the situation and gets them to decompress with a puzzle or a book.
“It’s very hard for any parent to have to parent in public,” Dr. Rebecca Chicot, founder of Essential Parent and the author of the Calm and Happy Toddler, told the outlet. “She seems to be good at making warm contact ‘touch to the head’ which is a nice connection. She gets down to their level to talk to them but let's them be children. She has a lovely balance of sensitivity and gentle boundaries. She doesn't expect them to behave like little adults and knows that children go through perfectly natural stages like tantrums.”
As Chicot mentioned, when talking to children (her own or others), Middleton makes it a point always bends down to meet their eye-line. Why? Well, making eye contact with children fosters open communication. By meeting kids eye-to-eye, the duchess doesn’t assert her dominance and instead encourages children to express themselves on equal terms.