Object lesson: Show the children the tool box and ask them what it is. Ask them what might be inside. Take out the hammer.
Ask what a hammer can be used for. If multiple answers are given, they may be categorized into good uses of a hammer and bad ones. If no bad uses are suggested, you'll have to bring that up yourself. A hammer can be used as a weapon, to hurt someone.
Explain how the children are like the hammer. They can choose to be creative and help build things, or they can choose to do the wrong things. God gives them that choice. But he wants them to be in HIS tool box, and do his work.
