In her book, One Nation Under God (Onward, 2008), Dunbar (on p. 100) calls public education a “subtly deceptive tool of perversion.” She charges that the establishment of public schools is unconstitutional and even “tyrannical” because it threatens the authority of families, granted by God through Scripture, to direct the instruction of their children (p. 103). Dunbar, who has home-schooled her children and sent them to private schools, bases that charge on her belief that “the underlying authority for our constitutional form of government stems directly from biblical precedents.” (p. xv)
Now remember, Dunbar sits on a state committee that is charged with overseeing curriculum and textbook standards in public schools in Texas. This is equivalent to having a member of Al Qaeda serve as a deputy in the Department of Homeland Security. Why would someone who holds such views serve on a board that oversees education in Texas, unless she thinks it's her mission to undermine public education in Texas?
Texas is full of a particular brand of right-wing Christians who feel this way, who homeschool their kids or agitate for vouchers so they can send their kids to private fundamentalists schools. But of course for these Christian moralists, it's not good enough to opt out of a system they don't like; they also want to make sure our kids are learning about the "controversy" over evolution and properly praising both God and America in their classes. That's why people like Dunbar run for and get elected to these positions, in races that generally fly under the radar for most Texans, after which they promptly begin trying to undermine the teaching of science in Texas public schools.
Dunbar's a nut, but she's only the most outspoken one. There are plenty more where she came from, running for and getting elected to state and local school boards or donating money to State reps and Senators who'll take up their cause of taking over public education in Texas, and it would be a mistake to think that her isolated comments are not reflective of their attitudes in general.