I am wondering if he might not have realized he did anything wrong while he was doing it, and is then afraid to admit because he is feeling bad when he realizes his mistake. Some children have trouble remembering the rules of behavior, or they may have trouble with controlling their impulses. Does it seem as if this is true? It sometimes looks like defiance.
Dear Ms. Jones,
Yes, to some extent it is normal for young children to lie to escape trouble for wrongdoing. You are correct in helping him to learn that you value honesty and that lying will actually compound the difficulty.
You can employ a variety of disciplinary tactics, depending on where your leverage is. A component of the discipline should be time out - e.g., for a 30-minute period. You can also add some restriction, depending on what your son likes. For example, if he enjoys TV, you can suspend TV viewing for a day. If he likes to ride his bicycle, you can suspend that for a day, etc.
Remember, too, to reward him when he is honest by expressing your pleasure.
Finally, maintain your composure. There's no need to be driven to distraction by his behavior. If you let yourself become emotionally upset by it, you'll only be adding to the problem.