34 C.F.R. §300.347.  Content of IEP.

(a) General. The IEP for each child with a disability must include--
...

(7) A statement of--
        (i) How the child's progress toward the annual goals described in paragraph (a)(2) of this section will be measured; and
        (ii) How the child's parents will be regularly informed (through such means as periodic report cards), at least as often as parents are informed of their nondisabled children's progress, of--
            (A) Their child's progress toward the annual goals; and
            (B) The extent to which that progress is sufficient to enable the child to achieve the goals by the end of the year.