 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued December 5, 2017                 Decided May 1, 2018

                        No. 16-7113

Z. B., A MINOR, BY HER PARENTS AND NEXT FRIENDS, ET AL.,
                      APPELLANTS

                              v.

    DISTRICT OF COLUMBIA, A MUNICIPAL CORPORATION,
                       APPELLEE


        Appeal from the United States District Court
                for the District of Columbia
                    (No. 1:15-cv-01037)


    Michael J. Eig argued the cause and filed the briefs for
appellants.

     Richard S. Love, Senior Assistant Attorney General,
Office of the Attorney General for the District of Columbia,
argued the cause for appellee. With him on the brief were Karl
A. Racine, Attorney General, Todd S. Kim, Solicitor General at
the time the brief was filed, and Loren L. AliKhan, Solicitor
General.

   Before: MILLETT and PILLARD, Circuit Judges, and
WILLIAMS, Senior Circuit Judge.

    Opinion for the court filed by Circuit Judge PILLARD.
                               2
     PILLARD, Circuit Judge: Z.B. is an elementary school
student who, from pre-kindergarten through third grade,
attended the Phoebe Hearst Elementary School in the District
of Columbia Public Schools system (DCPS). Her parents claim
that DCPS failed to offer Z.B. a fourth grade education
appropriate to her needs under the Individuals with Disabilities
Education Act (IDEA or Act). Because they thought the
education at Hearst was deficient, they withdrew Z.B. in the
summer of 2014 and enrolled her at the Lab School, a private
school for children with disabilities. By all accounts, Z.B. did
well at the Lab School. DCPS, however, stands by the
adequacy of the individualized education programs (IEPs)
Hearst offered, so it denied Z.B.’s family reimbursement under
the IDEA of the tuition costs at the Lab School.

     On cross-motions, the district court granted summary
judgment for DCPS. The court determined that DCPS, after
reviewing and responding to diagnostic information and action
requests from Z.B.’s parents, offered Z.B. an adequate
education. The Supreme Court thereafter, in Endrew F. ex rel.
Joseph F. v. Douglas County School District RE-1, 137 S. Ct.
988 (2017), raised the bar on what counts as an adequate
education under the IDEA. Endrew F. held that the Act
requires education “reasonably calculated to enable a child to
make progress in light of the child’s circumstances”—a
standard that the Court described as “markedly more
demanding than the ‘merely more than de minimis’” standard
the Tenth Circuit had applied, id. at 999-1000, and that also
appears more demanding than the district court’s approach
here, see Z.B. v. District of Columbia, 202 F. Supp. 3d 64, 75-
80 (D.D.C. 2016). In requiring more than merely some
“educational benefits,” id. at 77 (quoting Bd. of Educ. v.
Rowley, 458 U.S. 176, 207 (1982)), the Court in Endrew F.
stressed that “every child should have the chance to meet
challenging objectives,” and that a student’s “educational
                                3
program must be appropriately ambitious in light of his
circumstances.” 137 S. Ct. at 1000.

     The district court ably and extensively engaged the record
in this case, but we discern certain errors in the legal standards
it applied. The court excused arguable shortfalls in the IEP
DCPS offered to Z.B. in June 2014 because of “the short time
frame between the eligibility determination and the adoption of
the initial IEP.” 202 F. Supp. 3d at 80. The court did not
explain, however, why that short time frame was not DCPS’s
own fault. The IDEA places affirmative obligations on
schools, but the district court appears to have accepted DCPS’s
passivity: Z.B.’s parents, not DCPS, finally procured the
evaluations used for the 2014 IEP. And the court affirmed the
administrative finding that the 2014 IEP was adequate in part
because, when the school “was made aware” by Z.B.’s parents
of their “issues” with an initial version of that IEP, the school
“agreed to all of plaintiffs’ proposed changes.” Id. It thus
remains unclear whether and how DCPS itself made a valid
assessment of Z.B.’s needs before it offered the 2014 IEP—and
so whether that IEP was adequate.

     The district court also faulted Z.B.’s parents for failing to
show that Z.B.’s special education needs could not be met
“within DCPS.” Id. at 66; see id. at 75-79. But the legal issue
is not whether, as a general and hypothetical matter, the school
system as a whole somehow could have met Z.B.’s needs; it
was not Appellants’ burden to show that any possible
placement in DCPS “was not a viable option” or “would not
have worked.” Id. at 76-77. The issue, rather, is whether each
of the IEPs that Hearst actually proffered was adequate at the
time; if not, DCPS may be responsible to pay for an education
that was.
                                4
    Given the legal standard the district court actually applied,
we are not confident that DCPS met its duty under Endrew F.
to evaluate Z.B. and offer a 2014 IEP that adequately
responded to her needs: Was it too little, too late? We thus
vacate and remand for further consideration of the substantive
adequacy of Z.B.’s 2014 IEP under the standards of the IDEA
as Endrew F. and this opinion describe them.

     The second IEP DCPS offered in 2015, which Z.B.’s
parents also challenge as inadequate, is a different story. By
the time it composed the 2015 IEP, DCPS had fully
familiarized itself with Z.B.’s individual circumstances and
needs. Hearst had by then made its own evaluation of the
information Z.B.’s parents and the Lab School provided, and
conducted its own further assessments of Z.B. The record
shows that the IEP DCPS offered Z.B. in 2015 was supported
by the requisite analysis of Z.B.’s circumstances, and that it
was reasonably calculated to afford her an opportunity to make
progress in light of her particular circumstances. We
accordingly affirm the decision of the district court as to the
adequacy of the 2015 IEP.

                                I.

                                A.

     The IDEA, 20 U.S.C. § 1400 et seq., offers states federal
funding to provide a “free appropriate public education” to
students with disabilities, id. § 1412(a)(1)(A). The IDEA
details evaluation procedures that schools must use to
determine precisely what services an eligible child should
receive. See id. §§ 1414(a)-(b); see also 34 C.F.R. § 300.301,
300.304-06. Operationally, when a school has reason to
believe that a child with a disability is not receiving an adequate
education, see 20 U.S.C. § 1412(a)(3), it must first take
initiative to “review existing evaluation data,” including those
                                  5
the parents may have provided and observations of teachers
and other professionals, “before” it begins providing services
under the IDEA. Id. §§ 1414(a)(1)(A), (c)(1)(A). “[O]n the
basis of that review, and input from the child’s parents,” the
school must “identify what additional data, if any, are needed
to determine” the child’s current needs and skills. Id.
§ 1414(c)(1)(B). The burden is on the school to “ensure that
. . . the child is assessed in all areas of suspected disability.” Id.
§ 1414(b)(3)(B).         If the school determines additional
assessment is needed, the school is responsible for conducting
that assessment. Id. § 1414(c)(2). If, however, the school
determines no more data is needed to create an adequate
educational program tailored to the student’s needs, it must so
notify the child’s parents and inform them of their right to
request further assessment. Id. § 1414(c)(4).

     With the “results of [that] initial evaluation” before it, the
school and the parents—together, the “IEP Team,” see id.
§ 1414(d)(1)(B)—must design an individualized education
program. Id. § 1414(d)(3)(A)(iii). An IEP operationalizes a
specific student’s appropriate educational plan: It sets out, in
writing, the student’s existing levels of academic and
functional performance, establishes appropriate goals, and
describes how the student’s progress toward those goals will be
measured. Id. § 1414(d)(1)(A)(i)(I)-(III); see id. § 1401(9)(D).
Failure to follow those procedures is actionable where it denies
the child an appropriate education. Id. § 1415(f)(3)(E)(ii)(I).

     Substantively, the IDEA “requires an educational program
reasonably calculated to enable a child to make progress
appropriate in light of the child’s circumstances,” Endrew F.,
137 S. Ct. at 1001, even as it stops short of requiring public
schools to provide the best possible education for the individual
child, Rowley, 458 U.S. at 200, or an education “equal” to that
of non-disabled peers, Endrew F., 137 S. Ct. at 1001; Rowley,
                                 6
458 U.S. at 198-99. If a school system fails to provide a student
with an appropriate education and such education is offered at
a private school, the school system may be liable to reimburse
the student for the cost of private education. See 20 U.S.C.
§ 1412(a)(10)(C)(ii); see generally Leggett v. District of
Columbia, 793 F.3d 59 (D.C. Cir. 2015).

                                B.

     Z.B. began her schooling in pre-kindergarten at DCPS’s
Hearst Elementary School. Because Hearst was not Z.B.’s
neighborhood school, she was able to enroll there only after
winning a place through a DCPS lottery.1 In their initial
administrative complaint, Z.B.’s parents claimed they first
noticed in pre-kindergarten that Z.B. struggled to pay attention
and that her impulsivity and disorganization increasingly
affected her daily functioning and ability to learn at school.
The record contains neither evidence of any steps taken by
DCPS to evaluate Z.B. during her pre-kindergarten or
kindergarten years for possible disabilities, nor any direct
explanation that such steps were unnecessary.

     Z.B.’s first and second grade experiences were marked by
bullying and other interpersonal conflicts between Z.B. and
other students, which her parents claim prompted Z.B. to
behave inappropriately and negatively affected her academic
progress. Nothing in the record suggests that DCPS then
evaluated Z.B. to determine whether she was eligible for
special education under the IDEA. Concerned about her
behavior and academic performance, Z.B.’s parents took her in
the spring of her second grade year for a private psychological
evaluation at their own expense. In March 2013, a doctor at
Children’s National Medical Center (Children’s) diagnosed

1
  Unless noted otherwise, the facts recounted are drawn from the
administrative record before the Hearing Officer and District Court.
                                7
Z.B. with “[a]ttention deficit hyperactivity disorder combined
type” (ADHD). That doctor also recommended that Z.B.
receive a functional behavioral assessment.

    Z.B.’s parents hired a therapist at Children’s to work with
Z.B. soon after that diagnosis. On May 1, 2013, near the end
of Z.B.’s second grade year, the therapist wrote DCPS to
recommend developing a Section 504 plan for Z.B. A Section
504 plan, named after the section of the Rehabilitation Act of
1983 in which it was established, defines and commits to
provide public support for persons with disabilities. See 29
U.S.C. § 701 et seq.; see generally Fry v. Napoleon Cmty. Sch.,
137 S. Ct. 743, 749-50 (2017). While the IDEA applies to all
school-aged children, 20 U.S.C. §§ 1401(3)(A), 1412(a)(1),
Section 504 applies more broadly to federally financed
programs or activities, requiring as a condition of public
funding that recipients provide certain accommodations for
physically or mentally impaired individuals, 29 U.S.C.
§§ 705(20)(A), 794(a)-(b), and, in the school context, requires
a free, appropriate education for students with qualifying
disabilities, 34 C.F.R. § 104.33.

     DCPS developed a Section 504 plan for Z.B. within two
weeks of receiving the private therapist’s request. The plan
provided for classroom accommodations such as simplified
directions, extra time, and preferential seating in the classroom
to minimize distractions. After DCPS implemented the Section
504 plan, Z.B.’s father periodically contacted the school with
concerns about the slow pace of Z.B.’s progress. He testified
that, after DCPS implemented Z.B.’s section 504 plan, school
officials were “dragging their feet on getting” Z.B. tested. Joint
App’x (J.A.) 326.

     Z.B.’s parents report that her “situation came to a head”
after she received a threatening note on the playground in the
                               8
spring of third grade. J.A. 9, 129. They maintain that Z.B.
experienced significant distress in the period following the
note, including bouts of insomnia and physical illness. Her
parents alleged in their administrative complaint that, though
Z.B.’s struggles did not subside, DCPS failed to refer her for
special education and still refused to test her for learning
disabilities. Instead, Z.B.’s parents—again at their own
initiative and expense—took her for a psychiatric evaluation at
Children’s.

     In May 2014, licensed psychologist Dr. Jacqueline Sanz,
an expert in neuropsychology, oversaw the evaluation. Her
report concluded that Z.B. had ADHD, “weakness” in math and
written expression, attention and executive functioning
challenges, and “problems with anxiety, depressed mood,
oppositional behavior, and social skills.” J.A. 56-57. Dr. Sanz
also reported Z.B. struggled with impulsivity, inattention, and
“mood dysregulation.” J.A. 58. Based on her evaluation, Dr.
Sanz recommended that Z.B. receive specialized instruction,
classroom accommodations, and various therapies to support
her learning. Z.B.’s parents shared the report with Z.B.’s
teacher and principal at Hearst.

     In May 2014, near the end of Z.B.’s third grade year—four
school years into an elementary school experience that by
Z.B.’s parents’ account was not working from its start—
Hearst’s principal scheduled an IEP eligibility meeting. The
meeting was scheduled at Z.B.’s parents’ request, to respond to
the report that Z.B.’s parents had obtained from Dr. Sanz.

    Within approximately two weeks of receiving Dr. Sanz’s
report, DCPS developed the 2014 IEP for Z.B. That IEP
described Z.B.’s then-current levels of achievement and set
goals for her in math, written expression, and emotional, social,
and behavioral development. It provided that Z.B. would
                                9
receive one hour per day of specialized math education outside
the general classroom, thirty minutes per day of specialized
written expression instruction within the general classroom,
and one hour per week of behavioral support services outside
the general classroom. It also provided that Z.B. would
continue to receive the services called for in her Section 504
plan. DCPS put the IEP into effect immediately.

     Four days later, a week and a half before the scheduled end
of the school year, Z.B.’s parents withdrew her early from
Hearst to enroll her in a summer camp session that began before
the public school semester concluded. Then, on August 28,
2014, Z.B.’s mother notified Hearst that she was withdrawing
Z.B. and would instead enroll her at the Lab School, a private
K-12 day school in the District for students with learning
disabilities. Z.B. began her fourth grade year (2014-15) at the
Lab School, which developed an IEP for her in mid-October of
2014.

     Late in 2014, pursuant to its statutory obligation to provide
an IEP every school year for each eligible child in the
jurisdiction, see 20 U.S.C. § 1414(d)(2)(A), DCPS for the first
time conducted its own formal evaluations of Z.B. to prepare
to develop its 2014-15 IEP for her (hereinafter 2015 IEP). A
DCPS social worker in November 2014 administered a
functional behavioral assessment by observing Z.B. at the Lab
School and interviewing her, her parents, and her teachers.
DCPS also administered an occupational therapy assessment
around the same time.

     In December of 2014, with Z.B. attending the Lab School,
Z.B.’s parents met with the DCPS IEP team to discuss possible
revisions to its draft of this second IEP. DCPS worked to
update Z.B.’s IEP and, by January 2015, finalized a program
that contemplated serving her educational needs at Hearst.
                               10
     The DCPS 2015 IEP provided for nine hours of specialized
instruction per week outside the general classroom (five in
math, three in written expression, and one in reading), and one
hour per week of specialized reading instruction in the general
classroom. On top of those instructional services, the IEP
included two hours per month of behavioral support services
outside and another two hours per month inside the general
classroom; half an hour per week of occupational therapy
outside the general classroom; and half an hour per month of
occupational therapy consultation. That IEP incorporated all
of the information offered and requests made by Z.B.’s parents
and lawyer, but specified that Z.B. would attend Hearst. She
would have received some of her education inside the general
classroom there rather than all of it in the special-education
classroom as she did at the private Lab School—which
exclusively serves students with disabilities, and which her
parents preferred.

                               C.

     Z.B.’s parents then filed a due process administrative
complaint against DCPS. An impartial hearing officer at the
D.C. Office of the State Superintendent of Education oversaw
three days of testimony from several witnesses. In a
determination that the district court described as unworthy of
deference because it lacked “a detailed and reasoned
explanation of how the evidence supports its findings and
conclusions,” 202 F. Supp. 3d at 74, the hearing officer held
that the 2014 and 2015 DCPS IEPs were both reasonably
calculated to provide Z.B. an appropriate education, so DCPS
owed Z.B.’s parents no reimbursement, see Hearing Officer
Determination at 10-13. The hearing officer held that DCPS
did not deny Z.B. an appropriate education by failing to include
certain requested goals and additional special instruction, or by
setting Hearst, rather than a full-time special-education school,
                                11
as her educational institution. DCPS also did not fall short, the
hearing officer held, by relying on “the information the [IEP]
team had at the time,” including outside evaluations and
recommendations—all of which were provided by Z.B.’s
parents—“even though other assessments were needed.” Id. at
10-11.

     Z.B.’s parents filed suit in district court challenging the
hearing officer’s determination. On cross motions for
summary judgment, the court held that both of DCPS’s IEPs—
for 2014 and 2015—were reasonably calculated to provide
Z.B. an appropriate education. The court first asked “whether
removing Z.B. from DCPS is necessary to provide her with an
education that is ‘reasonably calculated to enable the child to
receive educational benefits’” within the meaning of Rowley.
202 F. Supp. 3d at 77 (quoting 458 U.S. at 207). It answered
in the negative: Nothing in Dr. Sanz’s report, the court
reasoned, expressly or implicitly determined that Z.B. required
full-time special education, id. at 75-76, and evidence of Z.B.’s
later progress at the Lab School did not show that Hearst was
unable to serve Z.B.’s educational needs, id. at 76-77.

     Regarding the 2014 IEP in particular, the court concluded
that, measured principally against the descriptions and
recommendations in Dr. Sanz’s report, that IEP was reasonably
calculated to enable Z.B. to make educational progress. Id. at
79-80. As part of the adequacy analysis, the district court
emphasized DCPS’s responsiveness under time pressure. Id.
at 80. The 2015 IEP, too, was substantively adequate in the
district court’s view: It addressed all of Z.B.’s identified needs,
so offered Z.B. an appropriate education for the balance of the
2014-15 school year. Id. The court accordingly concluded that
Z.B.’s parents were not eligible for reimbursement for Lab
School tuition. Id. at 81.
                               12
    Z.B.’s parents appealed.

                               II.

     The question before us is whether DCPS denied Z.B. a
free, appropriate public education. The IDEA requires an
education “reasonably calculated to enable a child to make
progress appropriate in light of the child’s circumstances.”
Endrew F., 137 S. Ct. at 999. Understanding the particulars of
a child’s current skills and needs is critical to developing an
“individualized” educational plan: “An IEP is not a form
document. It is constructed only after careful consideration of
the child’s present levels of achievement, disability, and
potential for growth.”             Id. (citing 20 U.S.C.
§§ 1414(d)(1)(A)(i)(I)-(IV), (d)(3)(A)(i)-(iv)).       As noted
above, the Act extensively details information-gathering
procedures to ensure that school systems provide children with
qualifying disabilities an education tailored to their distinctive
needs. See 20 U.S.C. § 1414(d)(3)(A); see also id. §§ 1414(a)-
(c).

     Z.B. does not argue that DCPS failed to meet its threshold
“child find” obligation—that is, to make its initial
identification of Z.B. as a student qualifying for services under
the IDEA. And DCPS does not dispute that, as of the time of
her IEP eligibility meeting, Z.B. was eligible for an IEP. The
parties’ dispute centers on the substantive adequacy of the
education DCPS offered to Z.B.—in particular, in the 2014 and
2015 IEPs.

     The evaluation and information-gathering procedures of
the IDEA are designed to position the IEP team—composed of
both school personnel and parents—to create an IEP tailored to
the student’s special educational needs. Failure to follow those
procedures may yield an IEP that is not appropriately tailored
to the student, denying her an appropriate education. See id.
                              13
§ 1415(f)(3)(E)(ii); Leggett, 793 F.3d at 67. We consider the
shortcomings Z.B.’s parents complain of in DCPS’s
information-gathering process to determine whether the IEPs
DCPS offered substantively fell short of what the IDEA
requires.

    Where, as here, a district court grants a motion for
summary judgment on the administrative record without
accepting additional evidence, we are on appeal “in exactly the
same position as the district court” and accordingly “review its
decision de novo.” Reid ex rel. Reid v. District of Columbia,
401 F.3d 516, 522 (D.C. Cir. 2005). Like a district court, we
must give “due weight” to the hearing officer’s determinations,
Rowley, 458 U.S. at 206, but we afford “less deference than is
conventional in administrative proceedings,” especially when
the decision is insufficiently supported by fact or reasoning,
Reid, 401 F.3d at 521 (internal quotation marks omitted). As
the party seeking relief, Z.B. bore the burden of proof at the
hearing, see Schaffer ex rel. Shaffer v. Weast, 546 U.S. 49, 51
(2005), and bears the burden of persuasion on appeal, see Reid,
401 F.3d at 521.

                              A.

     Appellants challenge the 2014 IEP that DCPS offered to
Z.B. at Hearst Elementary School as inadequate in several
respects. Appellants contend that the IEP was substantively
inadequate in the math and writing goals it set for Z.B., which
they claim were too high given her current skill levels, and in
lacking a reading goal, appropriate types and hours of
instruction, specific executive functioning goals, and
occupational therapy services. Across those substantive areas,
in Appellants’ view, DCPS dropped the ball on obtaining the
information needed to provide Z.B. with an adequate and
tailored IEP, including by failing to perform a functional
                               14
behavior assessment. See, e.g., J.A. 9, 12; Hearing Officer
Determination at 10, 11. As a result, they contend that the 2014
IEP was not reasonably calibrated to Z.B.’s needs, as measured
against what the school should have known about them at the
time, and they say those perceived shortcomings are confirmed
by later assessments of Z.B. in preparation for the 2015 IEP.

     Because an IEP must be tailored to the student’s
reasonably known needs at the time it is offered, the underlying
evaluation of the student is fundamental to creating an
appropriate educational program. “The IEP is the means by
which special education and related services are ‘tailored to the
unique needs’ of a particular child.” Endrew F., 137 S. Ct. at
994 (quoting Rowley, 458 U.S. at 181). The evaluation
requirement “serves a critical purpose: it allows the child’s IEP
Team to have a complete picture of the child’s functional,
developmental, and academic needs, which in turn allows the
team to design an individualized and appropriate educational
plan tailored to the needs of the individual child.” Timothy O.
v. Paso Robles Unified Sch. Dist., 822 F.3d 1105, 1119 (9th
Cir. 2016); see id. at 1110-11, 1124-25.

      The Act welcomes parental input, but specifically charges
the evaluation of the student and the framing of an adequate
IEP to the school. To be sure, that evaluation does not always
require a school to conduct additional testing. When “existing
. . . evaluations and information provided by the parents” and
“observations by teachers” and other professionals provide the
IEP Team with a reasonable picture of the student’s skills and
needs, the school may finalize an IEP without any further
testing unless requested by the child’s parents.             Id.
§§ 1414(c)(1)(A)-(B), (c)(4).

    Applying the IDEA as interpreted in Endrew F., we must
ask whether, in developing the 2014 IEP, DCPS adequately
                                15
evaluated Z.B.’s particular needs and offered her an IEP
tailored to what it knew or reasonably should have known of
her disabilities at the time. See Endrew F., 137 S. Ct. at 999.
Without the requisite assessment of Z.B.’s needs as of the time
the 2014 IEP was drafted, neither the IEP team nor reviewing
officer nor the district court could determine what services
were needed to provide an appropriate education, nor could we.
As the Second Circuit has explained, for example, the failure
to conduct an adequate functional behavioral assessment is a
procedural violation that can have substantive effects, “because
it may prevent the [IEP team] from obtaining necessary
information about the student’s behaviors, leading to their
being addressed in the IEP inadequately or not at all. . . . [S]uch
a failure seriously impairs substantive review of the IEP
because courts cannot determine exactly what information [a
functional behavioral assessment] would have yielded and
whether that information would be consistent with the student’s
IEP.” R.E. v. N.Y.C. Dep’t of Educ., 694 F.3d 167, 190 (2d Cir.
2012).

    The key inquiry regarding an IEP’s substantive adequacy
is whether, taking account of what the school knew or
reasonably should have known of a student’s needs at the time,
the IEP it offered was reasonably calculated to enable the
specific student’s progress. See Endrew F., 137 S. Ct. at 999.
As the district court aptly explained, that standard calls for
evaluating an IEP as of “the time each IEP was created” rather
than with the benefit of hindsight. 202 F. Supp. 3d at 75-76.
At the same time, the district court observed, evidence that
“post-dates” the creation of an IEP is relevant to the inquiry to
whatever extent it sheds light “on whether the IEP was
objectively reasonable at the time it was promulgated.” Id. at
76 n.23.
                               16
     Taking as the statutory baseline that DCPS had an
affirmative obligation to adequately assess Z.B’s needs, and
that the object of our evaluation is the IEP that DCPS offered,
we highlight two shortfalls in the district court’s analysis that
call for remand:

     First, in holding that the 2014 IEP was reasonably
calculated to provide Z.B. with an appropriate education, the
district court emphasized the school’s responsiveness. The
IDEA does, to be sure, require schools to respond meaningfully
to parents’ reasonable requests. See generally Leggett, 793
F.3d 59, 68-70. But merely reacting when parents complain is
not enough. A school has an affirmative obligation to “conduct
a full and individual initial evaluation” of an eligible student
“before” it begins providing services.              20 U.S.C.
§ 1414(a)(1)(A). If it considers only whatever information
parents pass along, a school may miss what reasonable
evaluation would uncover and, as a result, offer an inadequate
education.

     DCPS is not absolved of its statutory obligations to
appropriately evaluate Z.B. simply because it offered an IEP in
response to her parents’ formal request for one. The district
court generally recognized the school’s obligation to evaluate
Z.B., 202 F. Supp. 3d at 66-67, and was aware of potential
inadequacies in the 2014 IEP, see id. at 79 (acknowledging
evidence supporting parents’ critiques); Hearing Officer
Determination at 10-11 (acknowledging that additional
assessments were needed). It excused those concerns,
however, in part because of the “short time frame between the
eligibility determination and the adoption of the initial IEP,”
and the school’s willingness to address Z.B.’s parents’ specific
complaints once they raised them. Id. at 80. The Act expects
schools with reason to believe that a student may be suffering
from a disability to evaluate the student promptly and
                               17
appropriately. See 20 U.S.C. § 1412(a)(3). When data are
needed to understand a child’s unique needs, it is the school
that “shall” administer the necessary assessments.           Id.
§§ 1414(c)(1)(B), (c)(2). Z.B. had been a student in the DCPS
system for several years; even if Z.B.’s parents had never made
any requests whatsoever, once DCPS was or should have been
aware of Z.B.’s potential special educational needs, it was
obligated to evaluate her.

     To the extent that the district court relied on the premise
that DCPS only needed to respond to the requests Z.B.’s
parents made and incorporate the evaluations Z.B.’s parents
provided, that was error. Of course, a school’s ready
agreement with parents to provide services is not in itself
evidence (even if coupled with later additions of further
remedial measures) that the district had been ignoring an
obvious problem. Because, however, the district court did not
directly address what DCPS would have known had it met its
own obligation to evaluate Z.B. rather than waiting for and
reacting to her parents’ evaluations, it is not clear from the
proceedings below whether DCPS would have learned
anything more or different. If it would have, Z.B. may well
have been entitled to a substantively different IEP from the one
DCPS offered her in June 2014.

     As things stand, we cannot discern whether the 2014 IEP
was in fact tailored to Z.B.’s needs. It is not enough to say, as
the district court and DCPS did, that the 2014 IEP accorded
with the recommendations of Dr. Sanz’s May 2014 report. See
202 F. Supp. 3d at 79-80. A reviewing court must answer the
predicate question whether—combined with all other relevant
data—any assessment parents may have sought and funded on
their own provided a materially accurate and adequate account
of the student’s circumstances. While some parents may seek
out private evaluations and bring them to the school’s
                               18
attention—as Z.B.’s parents have commendably done here—
not all parents have the resources or expertise to obtain an
accurate evaluation. See Eloise Pasachoff, Special Education,
Poverty, and the Limits of Private Enforcement, 86 Notre
Dame L. Rev. 1413, 1437-39 (2011). Yet all students with
disabilities, regardless of their parents’ involvement or ability,
are entitled under the IDEA to receive IEPs reasonably
calculated to enable their educational progress. The school
may not simply rubber stamp whatever evaluations parents
manage to procure, or accept as valid and sufficient whatever
information is already at hand.

     Because the district court did not question whether DCPS
needed additional or different metrics of Z.B.’s skills to
develop the June 2014 IEP, it failed to establish a reliable
baseline of Z.B.’s current needs against which to evaluate the
IEP’s adequacy. The district court recognized that “[t]here
[was] evidence that supports plaintiffs’ specific criticisms of
the June 2014 IEP.” 202 F. Supp. 3d at 79. In evaluating it,
the court first looked for “fatal inconsistencies between the
Sanz Report and the June 2014 IEP,” id., assuming the Sanz
report sufficed as a measure of Z.B.’s needs. Somewhat in
tension with that approach, the court did not consistently
identify what data the school used when it set baselines and
goals that departed from Dr. Sanz’s evaluation. The district
court relied on testimony of DCPS officials in accepting the
IEP’s lack of reading goals, id. at 80, but pointed to no
testimony or other evidence in excusing the discrepancies
between the Sanz report and the 2014 IEP for math and writing
goals, id. at 79-80. In reviewing Z.B.’s contention that the IEP
should have included occupational therapy goals, the court did
not fault DCPS’s non-responsiveness to testimony that “Z.B.’s
need for occupational therapy was probably longstanding,” id.
at 73, only because of the “short time frame between the
eligibility determination and the adoption of the initial IEP,”
                               19
id. at 80. Neither the district court’s opinion nor the parties’
briefing reveals whether or on what ground DCPS may have
reasonably concluded that the IEP was tailored to Z.B.’s needs
at that time.

     Appellants contend that the content of the 2015 IEP, which
offered Z.B. more specialized instruction, proves that the 2014
IEP did not take full account of Z.B.’s needs. DCPS counters
that the later IEP is not relevant to the question whether the
earlier IEP was adequate. The district court correctly rejected
DCPS’s contention that, in reviewing the IEP, the court could
not consider “any evidence that was not before the IEP team at
the time the IEP was adopted.” 202 F. Supp. 3d at 76 & n.23.
Sometimes a belatedly obtained professional opinion, for
example, may suggest a longstanding problem that a school
should have but failed to identify and account for earlier. At
the same time, the fact that the 2015 IEP offered more services
than its 2014 counterpart is not per se evidence that the 2014
IEP was inadequate.

     We do not know whether the June 2014 IEP in fact fell
short, in part because we do not know whether Z.B.’s needs, as
reflected in the 2015 IEP, were already present in June 2014.
The district court failed to grapple with whether, taking into
account DCPS’s duty to be proactive, Hearst should have
offered in the 2014 IEP the full range of services it eventually
offered in the 2015 IEP. We do not conclude that was the case,
nor do we say that it was not.

     Second, the district court further erred by placing an
inappropriately heavy burden on Z.B.’s parents in their
challenge to the 2014 IEP, requiring that they show that no IEP
that DCPS could have offered would have sufficed. The
district court correctly recognized that “the question before” it
was “not whether placement at the Lab School is appropriate”;
                              20
it erred, however, in framing as the right question “whether
placement in DCPS is not.” Id. at 76; see id. at 66. In
determining whether the offered IEPs were reasonably
calculated to provide Z.B. an appropriate education, the
pertinent question is what DCPS actually offered, not what it is
“capable of providing,” id. at 76 n.25. The district court gave
DCPS the benefit of any capacity it might potentially have
mustered when it faulted Z.B.’s parents for not having broadly
established that “removing Z.B. from DCPS is necessary” to
provide her with an IDEA-compliant education. Id. at 77.
Establishing that DCPS did not provide Z.B. an appropriate
education does not require, as the district court demanded,
“persuasive evidence that placing Z.B. in DCPS was not a
viable option.” Id. at 76.

     No parent can be expected to rule out the ability of an
entire school system to serve their child. Parents are only
promised the support articulated in the IEP. See R.E., 694 F.3d
at 185-87. The focus of a parent’s IDEA claim and the courts’
review is the IEP, not the school system’s overall capacities.
The IDEA does not permit us to sustain an inadequate IEP
because the school system theoretically might bolster it. Cf.
Leggett, 793 F.3d at 68-70. Under the IDEA, plaintiffs need
only prove the shortcomings of the IEP the school in fact
offered.

                             ***

     Because the district court accepted DCPS’s reactive mode,
and applied the wrong burden in requiring plaintiffs to show
that DCPS could not provide adequate services, we cannot
credit its determination that the 2014 IEP was adequate. We
remand to the district court to consider in the first instance
whether DCPS satisfied its obligation to assess Z.B. and offer
her a tailored IEP in June 2014. We do not here resolve the
                               21
specific challenges to the IEP. Deciding whether DCPS was
on notice that Z.B. needed additional support or evaluation
beyond what the IEP proposed requires a “fact-intensive”
inquiry. See Endrew F., 137 S. Ct. at 999. The parties present
conflicting accounts of the severity of Z.B.’s learning
challenges as of June 2014, and of what DCPS knew or should
have known and done in the circumstances.

     Should the parties seek to supplement the existing record,
the district court has authority under the IDEA to “hear [that]
evidence at the request of a party.”                20 U.S.C.
§ 1415(i)(2)(c)(ii); 202 F. Supp. 3d at 74 & n.21. Z.B. might
point to or introduce evidence of any aspect of her disability or
need for additional services that she contends DCPS should
have known at the time but failed to take into account in the
2014 IEP. For its part, DCPS might factually dispute whether
it knew or should have known of any need of Z.B.’s for
additional evaluations beyond what it considered in developing
the 2014 IEP.

                               B.

     Appellants also challenge the substantive adequacy of the
2015 IEP on the grounds that it lacked executive functioning
goals for Z.B. and failed to provide appropriate types and hours
of instruction. The record reflects that, in contrast to its
approach to the 2014 IEP, DCPS took an affirmative role in
collecting information to prepare for the 2015 IEP. DCPS staff
conducted a functional behavioral assessment and an
occupational therapy evaluation to measure Z.B.’s needs and
calibrate a tailored learning plan. Taking account of Z.B.’s
parents’ suggestions, the evaluations the parents provided,
those the Lab School provided, and DCPS’s own assessments
of Z.B.’s skills and needs, DCPS created a final IEP that
provided eight combined hours per week of out-of-class math
                               22
and writing assistance, one hour per week of out-of-class
reading assistance, behavioral support services, occupational
therapy services, and various other learning aids. In view of
Z.B.’s needs, as reflected in the body of assessments and
highlighted by specific requests, we hold that the 2015 IEP
offered Z.B. an appropriate education.

     The district court correctly concluded that the 2015 IEP
did not deny Z.B. an appropriate education for want of an
executive functioning goal, because DCPS addressed executive
functioning skills within the IEP’s treatment of other areas of
concern. DCPS staff testified that they typically treat executive
functioning as a crosscutting factor, rather than in a separate
section of the IEP. They do so because executive functioning
challenges present themselves distinctly in connection with
different areas the IEP addresses. Thus, the 2015 IEP set
various organizational goals for Z.B. and provided services
designed to enable her to achieve them. It described, for
example, coaching Z.B. to use techniques such as highlighting,
underlining, story-mapping, and self-questioning to help her
organize her work. The IEP afforded Z.B. extra time to
implement those organizational strategies in class. Appellants
therefore have not demonstrated any respect in which the IEP’s
treatment of executive functioning goals denied Z.B. an
appropriate education.

     Appellants also have not shown that the 2015 IEP lacked
appropriate types or hours of instruction. They contend,
essentially, that the 2015 IEP—which provided for, among
other things, nine hours of special education outside the general
classroom setting per week—did not provide Z.B. enough
small-group or individual education, especially by contrast to
the full-time special education offered at the Lab School.
                              23
     Without more, that argument runs up against the IDEA’s
imperative that, to “the maximum extent appropriate,” public
schools provide students with disabilities an education in the
“least restrictive environment” possible.          20 U.S.C.
§ 1412(a)(5)(A). Ordinarily, states must ensure “removal of
children with disabilities from the regular educational
environment occurs only when the nature or severity of the
disability of a child is such that education in regular classes
with the use of supplementary aids and services cannot be
achieved satisfactorily.” Id. The Supreme Court recently
affirmed that “the IDEA requires that children with disabilities
receive education in the regular classroom ‘whenever
possible.’” Endrew F., 137 S. Ct. at 999 (quoting Rowley, 458
U.S. at 202).

     Nothing in the record calls into question the
reasonableness of DCPS’s conclusion that Z.B. would benefit
developmentally from interaction with her non-disabled peers.
Appellants made no showing that further special education
services apart from the general student population were
required for Z.B.’s educational needs to be met. We thus
cannot fault DCPS for its decision, consistent with the least-
restrictive-environment mandate, to offer Z.B. substantial
portions of her instruction in general education classrooms
rather than in disability-specific groups.

    Appellants advance no argument or evidence claiming any
shortfall other than those two: inadequate attention to
executive functioning, and failure to provide for full-time
special education at the Lab School. We accordingly affirm the
decision of the district court that the 2015 IEP meets the
requirements of the IDEA.
                               24
                              III.

     The IDEA calls on public schools throughout the United
States to provide a free, appropriate education. Congress has
not committed to educational perfection: “Any review of an
IEP must appreciate that the question is whether the IEP is
reasonable, not whether the court regards it as ideal.” Endrew
F., 137 S. Ct. at 999 (emphasis in original). If there is a gap
between the best education that money can buy at a private
school for a student with disabilities and the free and
appropriate education at a public school that the IDEA
promises, one might justly hope to close that gap for all
students. Meanwhile, what Congress has required is that public
schools be “ambitious” for every child, giving each the
opportunity to “meet challenging objectives.” Id. at 1000.
Disabilities can be subtle and complex. They may require
expertise to identify accurately. The IDEA requires public
schools to be alert to the needs of all students they serve. They
must take steps to identify those students with disabilities and,
armed with all reasonably available information and expertise,
ensure that each IDEA-eligible student receives an education
appropriate to her needs.

    We affirm the district court’s holding that DCPS complied
with the IDEA in offering Z.B. the 2015 IEP, and remand for a
determination as to whether it did so when it offered her the
2014 IEP.

                                                    So ordered.
