I¡¯m not familiar with Sylvan Learning Center. My daughter is using beestar.org. It¡¯s a great web site for primary school students. It offers exercises of math, English language art, science, etc. My daughter is doing the math exercises. There are 2 exercises weekly. All the exercises are timed and there are corresponding invigorative mechanisms such as honor roll. That can improve the efficiency greatly when children doing the exercises.