“Children with disabilities” means children between the ages of 3 and 21 for whom it is determined, through definitions and procedures described in the Illinois Rules and Regulations to Govern the Organization and Administration of Special Education, that special education services are needed. An eligible student who requires continued public school educational experience to facilitate his or her successful transition and integration into adult life is eligible for such services through age 21, inclusive, which, for purposes of this Article, means the day before the student’s 22nd birthday, unless his or her 22nd birthday occurs during the school year, in which case he or she is eligible for such services through the end of the school year. An individualized education program must be written and agreed upon by appropriate school personnel and parents or their representatives for any child receiving special education.