She began the "second grade" this fall. When my husband plays Scrabble Junior with her, she is unable to spell one word accurately without asking my husband if it's right. I am wondering if there is a way to see if she up to par with kids her age. Her mother never completed school because she couldn't keep up, and we're hoping that her mother didn't choose the homeschool way as an excuse for her daughter.
Homeschooled students do not have to follow this pattern. Parents can tune in to their child's abilities, and structure their teaching methods to accommodate that child's learning style. Thus, some kids begin to read and spell at four, while others may not be ready until they are nine, ten, or even older. There is no particular advantage in learning to read or write early, and there is evidence to suggest that doing so can be harmful. For more information about this, read How Children Learn by John Holt.
Most six- or seven-year-old children, including those in traditional schools, do not spell well. If your stepdaughter appears to be having a difficult time spelling, it may not be a problem with homeschooling, but rather that she simply does not yet have the ability to grasp spelling concepts. My daughters hated Scrabble when they were six or seven, but couldn't get enough of the game just a few years later when they matured a bit. I suggest reading good books with your stepdaughter as an alternative activity. Reading aloud is a wonderful way to develop children's language skills.
The Homeschooling Book of Answers by Linda Dobson will help you better understand the homeschooling philosophy.