Do choose worksheets that are appropriate for the child's level, since children can get discouraged easily, if they are unable to perform the activity. Well illustrated worksheets with cartoons are also more likely to appeal to children. Worksheets that use common situations children come across at home, school, in the market place etc and that use common objects known to children would be more relevant.
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 K-12 digital education and cutting edge digital education materials will provide a comprehensive educational program for your homeschooled student in excellence and ease.