KhanAcademy.com features instructional videos and practice problems for fifth-grade math. IXL.com features only practice problems, but it covers a greater number of concepts than Khan Academy covers.
Khan Academy provides two- to three-minute instructional videos and sets of practice problems on fifth grade math concepts. From KhanAcademy.com, selecting Subjects, hovering over Math and selecting 5th Grade displays a list of fifth-grade math concepts. Selecting a topic displays a list of available videos and sets of quiz-style practice problems.
IXL provides practice problems as supplemental resources, but it does not provide instructional materials. From IXL.com, selecting Math and then Fifth-Grade Skills displays a list of math concepts covered in fifth grade. Selecting a topic displays a set of quiz-style problems.