The High Holidays are a wonderful time to dig deep and explore the value of "I'm sorry," with kids. While children may be too young for some of the rituals associated with Yom Kippur, like fasting, kids of all ages understand the weight of "saying sorry" and "doing better."
When explaining Yom Kippur to young children, it can be helpful to frame the holiday as "I'm Sorry Day."
Even good friends sometimes hurt each other and Yom Kippur is an opportunity to think about ways to improve and resolve mistakes. When people wrong us, we want them to acknowledge it and apologize, which is why we must do the same.