At its website, www.tfn.org, the TFN gives examples of cases where it believes ideology affected textbook decisions, such as the 2002 rejection of a history text with positive references to Islam and the environmental-science book in the current lawsuit, which some see as anti-free enterprise because it teaches about global warming.
Influence of this kind worries those who think such an approach confuses ideological standards with academic ones. But for some of the more conservative parent groups, ideology is exactly what they're trying to keep out of textbooks.
"Textbooks by and large are written by college professors," says Peggy Venable, state director for Citizens for a Sound Economy Foundation. "Many of us feel professors are more liberal than many parents are. We need to make sure information being taught is something parents feel comfortable with."
Ms. Venable's group also worries that accuracy in textbooks may be sacrificed to liberal goals such as political correctness.
Textbookmakers, they argue, sometimes rewrite history by overplaying the accomplishments of woman and racial minorities and editing out what they believe to be more important material.
"White males are often underrepresented," says Venable. "I see publishers as trying to meet requirements by putting women and minorities in [and] ignoring significant events."
In 1995 the Texas legislature passed a law stating that the state board of education may reject books only on the basis of factual errors and not due to disputes over ideology.
But at the same time, state law requires the board to approve books that promote democracy, patriotism, and the free-enterprise system - leaving the door open to disagreements of a more subjective nature.
In Texas, textbooks are updated in waves. Each year, different topics come up for revision. Under consideration this year are family studies, career studies, and biology. The subject of biology is usually the trigger for particularly fierce controversy.