"The term 'free appropriate public education' means special education and related services that (a) have been provided at public expense, under public supervision and direction, and without charge; (b) meet the standards of the State educational agency; (c) include an appropriate preschool, elementary, or secondary school education in the State involved; and (d) are provided in conformity with the individualized education program required under section 614(d)." [Section 602(8)]