359, 370, 105 S.Ct. 1996, 85 L.Ed.2d 385 (1985). The school has the burden of showing that a FAPE was offered. See Oberti v. Board of Educ. of Borough of Clementon School Dist., 995 F.2d 1204, 1219 (3d Cir.1993). To meet this burden, the school must establish that it complied with the procedures set out in the IDEA and that the IEP was “reasonably calculated” to enable the child to receive “meaningful educational benefits” in light of the child’s “intellectual potential.” See Board of Educ. of Hendrick Hudson Central School Dist., Westchester County v. Rowley, 458 U.S. 176, 206-07, 102 S.Ct. 3034, 73 L.Ed.2d 690 (1982); Ridgewood Bd. of Educ. v. N.E., 172 F.3d 238, 247 (3d Cir.1999). If the IEP did not provide a FAPE, the District Court must then decide whether the parents took appropriate actions. See Michael C. v. Radnor Twp. Sch. Dist., 202 F.3d 642, 651 (3d Cir.2000).
The burden of proof that a District Court must apply when an IDEA decision by a state agency is challenged is unusual. Although the District Court must make its own findings by a preponderance of the evidence, 20 U.S.C. § 1415(l)(2)(B)(iii), the District Court must also afford “due weight” to the ALJ’s determination. Rowley, 458 U.S. at 206, 102 S.Ct. 3034; see also Holmes v. Millcreek Tp. School Dist., 205 F.3d 583, 591 (3d Cir.2000). Under this standard, “[f]actual findings from the administrative proceedings are to be considered prima facie correct,” and “[i]f a reviewing court fails to adhere to them, it is obliged to explain why.” S.H. v. State-Operated School Dist. of City of Newark, 336 F.3d 260, 271 (3d Cir.2003). In addition, if a state administrative agency has heard live testimony and has found the testimony of one witness to be more worthy of belief than the contradictory testimony of another witness, that determination is due special weight. Id.; Carlisle Area School v. Scott P., 62 F.3d 520, 527-29 (3d Cir.1995). Specifically, this means that a District Court must accept the state agency’s credibility determinations “unless the non-testimonial, extrinsic evidence in the record would justify a contrary conclusion.” Carlisle, 62 F.3d at 529 (emphasis added). In this context the word “justify” demands essentially the same standard of review given to a trial court’s findings of fact by a federal appellate court. See Anderson v. City of Bessemer City, N.C., 470 U.S. 564, 574, 105 S.Ct. 1504, 84 L.Ed.2d 518 (1985).
When a District Court decision in a case such as this is appealed to us, we of course exercise plenary review with respect to the question whether the District Court applied the correct legal standards under the IDEA, see Polk, 853 F.2d at 181, but we review the District Court’s factual findings for clear error. T.R. v. Kingwood Tp. Bd. of Educ., 205 F.3d 572, 576 (3d Cir.2000) (citations omitted). “A finding of fact is clearly erroneous when, after reviewing the evidence, the court of appeals is left with a definite and firm conviction that a mistake has been committed.” Oberti, 995 F.2d at 1204 (internal quotation marks omitted).
III.
The District Court in this case did not properly apply the “due weight” standard. Both the ALJ and the District Court were confronted with, conflicting opinions by experts on the question whether placement at Shore offered P.S. an education that was sufficiently free from the threat of harassment to constitute a FAPE. The ALJ who heard the witnesses during a hearing that extended over four days credited the witnesses who opined that placement at Shore would have exposed P.S. to a continuation of the devastating bullying that had occurred in Middle