(A) A person knows, or acts knowingly or with knowledge of:
(1) The nature or attendant circumstances of his or her conduct, described by the section defining the offense, when he or she is consciously aware that his or her conduct is of that nature or that those circumstances exist. Knowledge of a material fact includes awareness of the substantial probability that the fact exists.
(2) The result of his conduct, described by the section defining the offense, when he is consciously aware that such result is practically certain to be caused by his conduct.
(B) Conduct performed knowingly or with knowledge is performed willfully, within the meaning of a statute using the latter term, unless the section clearly requires another meaning.
(ILCS Ch. 720, Act 5, § 4-5)