Use black poster board or construction paper to cut out hearts. Give each child a heart and explain that sometimes we can become hurt or hurt other people and make them feel sad in their hearts. Use white markers or white paint to cover up the blackness of each heart. Remind your children that when they forgive, it not only helps their own hearts feel better, but the hearts of the people they forgave.
Ask each child to write down a memory of a time they felt hurt by another person. It's OK to just write a single word if they can't express the entire memory. Take the papers and crumple them up. Explain that sometimes it's important to just forget about what happened in order to move on and forgive the other person. Take the crumpled pieces of paper and soak them in water until they dissolve and crumple away.
Wrap an empty box. Give your students stickers and markers with which to decorate the box. Talk to your students about forgiveness. Ask if they remember a time when they needed to ask forgiveness. Pass the box around the room and have each child mention a time when she had to ask for forgiveness, or if there's something she still needs to ask forgiveness for.
Explain to your preschoolers that sometimes it can be hard to forgive other people. If someone truly hurts you, forgiving them can be hard. Help your students draw pictures that reminds them of forgiving others. Ask them to give the picture to someone they love and care. Remind your students to share what they've learned about forgiveness with the person to whom they give their drawing.