This is a simple group-time activity for Pre-K and early elementary school kids. First, have the kids hold hands to sit down in a circle. Once seated, talk with them about how everyone possesses their own unique talents, strengths, and other positive qualities that others can like and appreciate. So to talk about these strengths, we're going to each take turns naming a positive quality about the child next to us. It can be an aspect of their personality, an act of kindness they once performed, a time when they were brave, a physical attribute such as their beauty or nice clothes, a sport they are good at, or any other likeable quality their classmate possesses. Before you start, explain that it may take some kids longer to name something because they don't know their classmate as well, not because that person has less likeable things about them. This will help to eliminate any hurt feelings should a child stall to think of something, as children commonly do.
Next, starting with one child, go down the circle and have them think about one nice thing they like about the kid next to them, either to the left or right (or both). Then after each child gives their compliment, add your own compliment as a teacher about that same child. This is an important variation; since it will help you serve as a counterweight and moderator to the sometimes shallow compliments the kids might serve up. When Johnny's friend tells him he likes his shoes, you can compliment Johnny on how well he shares with others, or how much energy he comes to school with. When one child gives a compliment about how nice the next child is, you might compliment her on her pretty eyes, especially if it's a less-attractive child who may seldom get compliments on her looks. Your input will also help get the kids thinking on their own about more character qualities, and less about superficial ones.
After you're through, talk about how nice it is to get compliments from others, and how we should try to give other people compliments about the good things they do whenever we have a chance. Simple things like saying how much we enjoy a meal someone provided to us, or complimenting a stranger (so long as our parents are around) about a pretty dress they have on can change someone's entire day for the better. Talk about how people often keep their compliments to themselves because it might feel awkward, but that this means we all get less of them. During a second group time later in the day, sit down with the kids as a group and create a list of all the different ways there are to offer simple compliments in everyday life.