Here is a link to Federal Regulations regarding children: Title 45 PART 46 Subpart D—Additional Protections for Children Involved as Subjects in Research.
Exemptions at §46.101(b)(1), (3) through (6) are applicable
The exemption at §46.101(b)(2) (educational tests) is also applicable...
the exemption at §46.101(b)(2) for research involving survey or interview procedures or observations of public behavior does not apply
The exceptions, additions, and provisions for waiver as they appear in paragraphs (c) through (i) of §46.101 of subpart A are applicable to this subpart.
"the IRB shall determine that adequate provisions are made for soliciting the assent of the children" (46.408a)
"the IRB shall determine ... that adequate provisions are made for soliciting the permission of each child's parents or guardian" (46.408b)
"Where... permission is to be obtained from parents, both parents must give their permission" (46.408b)
"Permission by parents or guardians shall be documented" (46.408d)
(source)