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.
Almost everything you do with your child can be turned into an opportunity to learn - and worksheets can give you the guidance you need to find those opportunities.
Ideally, children who have been introduced to reading modeling behavior enter kindergarten and first grade ready and eager to read on their own. For most children, the formal teaching of reading begins in these grades. Most educators, homeschool or otherwise, use a combination of phonics programs, worksheets, and actual books to teach reading. These are all tried and true methods and can result in reading success. A relatively new methodology, syllabics, extends the focus of phonics programs on the sounds associated with the consonant letters to simple rules for correctly using the variable sounds associated with the vowels.