***...despite claims that Henry is mentally ill and intellectually disabled. ***
Ever notice how the more vicious a black criminal is the more they plead “Mentally Ill”? Gets them life instead of the needle.
Somebody who knows he's going to grow up to be a street thug, has an early incentive to deliberately do badly on school testing, so that he can claim "intellectually disabled" as a defense. Even if they're too stupid to think of this, you can be sure they have people telling them this.