Object: A lock and key.

Good morning, boys and girls. I brought with me this morning a piece of equipment that all of you have seen and many of you have used. [Hold up a lock.] I am sure that all of you know what this is, but so that everyone who is here this morning knows what we are talking about, let’s say it out loud. What is this? That’s right, it is a lock. What do you use a lock for? [Let them list some of the uses.] Very good. I suppose that you would think that a good lock is pretty important. Now there is one thing missing from all of this that is just as important as the lock. Can you tell me what else you need to make this lock complete? [Let them answer.] That’s right, a key. Would any key do? I have a…