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.
Since 3rd grade math relies on the concepts that were learned during kindergarten, first and second grades, don't be afraid to start your child at a lower level.
The first step to teaching the above is strengthening the small muscles in the hands and wrists that are used in handwriting. This process is often referred to as building fine motor skills. You can encourage fine motor development by having your child use art supplies like crayons, paints, markers, glue and scissors.
A step-by-step set of preschool worksheets will introduce new challenges to your child - skills and concepts they have not yet learnt. With your support and encouragement, your child will learn these new skills, achieve their goals, and gain confidence that will be vital when they start kindergarten or school. Starting 'big school' brings a lot of changes into a child's life, and your child needs to believe that he or she can face new challenges and cope well.