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.
A comprehensive set of worksheets covering a variety of subjects can be used to expand your child's learning experience. A worksheet about shapes can be used as part of a game to find shapes around the house, counting worksheets can be used to count things you see in the grocery store and so on.
These are basically digital versions (like ebooks) of worksheets that can be bought and downloaded to your computer from the internet or from CDs and then printed out. The advantage is that you can print out whichever sheet you wish. If you need to re-inforce a certain concept more you can usually print out that sheet again. Of course you will therefore need to have a computer and a printer.
Lacing activities, stringing beads and cheerios, playing with playdoh, scooping sand or rice, and activities like pouring and stirring are also great fine motor activities.