Many online math games are designed purely for entertainment and won't do much in terms of teaching your child. While these games can be fun and engaging for third graders, you want to choose games that will practice the skills being taught in school.
This will include counting to ten, recognizing shapes and colors, being able to hold a pencil or crayon properly, and coloring in without scribbling. Basic math concepts such as recognizing patterns, understanding quantity and some simple addition and subtraction will be useful.
While there are many preschool worksheets available, some are more useful than others in terms of versatility. There is a lot more to school readiness that just knowing the alphabet and counting to ten.
A K-12 Digital education must provide creativity; customized learning based on the needs of the student, and cutting edge digital educational materials for grades kindergarten through 12th.