Cognitive impairment shall be manifested during the developmental period and be determined through the demonstration of all of the following behavioral characteristics:
(a) Development at a rate at or below approximately 2 standard deviations below the mean as determined through intellectual assessment.
(b) Scores approximately within the lowest 6 percentiles on a standardized test in reading and arithmetic. This requirement will not apply if the student is not of an age, grade, or mental age appropriate for formal or standardized achievement tests.
(c) Lack of development primarily in the cognitive domain.
(d) Impairment of adaptive behavior.
(e) Adversely affects a student's educational performance.
