Sometimes it's just a matter of finding the right way to present the material, though, that makes the difference and finally allows the information to register in your child's long term memory. Worksheets and computer games may not be doing the trick, for instance, because your child may be an auditory learner.
Auditory learners, and almost all students, really, can benefit from having material presented in ways that stimulate more of their brain. Combining music, rhythm, and visual cues can give your child's brain more ways to process and store the information, and to remember it later.