One idea to emphasize forgiveness is to take the children outside with their book bags and gather a pile of rocks. Have the children list things that other people do that make them mad. For each person they are angry at, put a rock in their book bag. The rocks should be heavy enough to weigh down each child. Tell them that holding on to anger gets heavy like the rocks they're carrying. Choosing to forgive releases that burden. Ask the children if they're ready to forgive and feel light again. Have them take the rocks out of their book bag and run around. For a biblical lesson, read the story of Joseph in the book of Genesis while they still have the rocks in their book bags.
Read the children books that teach about forgiveness in an age-appropriate manner. Books include: "Einstein's Enormous Error," by Sheila Walsh, about an elephant makes a mistake that gets himself and his friends in trouble, making them very angry with him; and "Ivy's Icicle: Book Three," which follows the story of Ivy and how she feels when her brother breaks her doll.
Have the children decorate a small cardboard box with paint, sticker and glitter. When they get mad a classmate and choose to forgive, they can put a cotton ball in their box. At week's end, the children can dump out their forgiveness boxes. Ask them if they can remember what they were upset about. Most likely they won't remember them all, placing an emphasis on offending acts not being important enough to be mad about. Another idea for a biblical craft is to give the children a heart made of black construction paper. Explain the black heart represents a sinful heart. Have them paint their black hearts white and explain that Jesus forgave us and wiped away our sins away, turning our hearts white like snow. Allow the children to exchange their hearts with someone they were upset with and tell them they forgive them.
Gather the children into a circle and have them toss a bean bag around. The person with the bean bag must say who they recently forgave. Make it more exciting by playing a hot potato version where they must pass the bean bag around until the music stops. Whoever has the bean bag has to say who they forgave before the game resumes. Another idea is to play forgiveness tag, a variation of freeze tag. Have one person go around tagging kids and they must stand frozen. Other students who haven't been tagged can untag them by tapping them and saying "I forgive you."