Some textbooks are better than others, but I would stress more on the concept of interpretation rather than accuracy. Now, accuracy does exist in history (ex: saying that the Civil War started in 1861, rather than 1860 which is incorrect), but far more important than names and dates are the choices that a textbook (or any historical study) makes when forming the narrative that it wants to tell. History is very interpretive, meaning that its not a process of deriving absolute truth but rather using the past as a form of societal reflection. To paraphrase a useful quote, it's the process of a leaf learning that its part of a tree. This process is fueled by historical sources (called primary sources). There are many of them coming from disparate voices which can contradict each other or even themselves, and sources can be themselves unreliable because they were usually created by humans who could have intentionally lied, been misinformed, or simply biased due to their own personal believes or perspective.

Historians use these primary sources to interpret the past and insodoing create secondary sources (like a book or article). Your textbook is what we call a tertiary source, meaning it's not a direct historical study but rather something derived from the combined efforts of many secondary sources. Your textbook may present a primary source sometimes (say, a speech from a president) but those are generally for illustrative purposes only. Tertiary sources are interpretations of interpretations. Evaluating your textbook is much more about how successfully this interpretive process is done rather than fact-checking it for accuracy. So ask of your textbook: Who and what is important, according to this book? Whose perspective is used here, and what's being ignored? What historical sources are being used here and are they sufficient? What questions does this book answer and not answer?

Check out James Loewen's Lies My Teacher Told Me, which breaks down a number of common American history textbooks for their interpretive strengths and weaknesses.

Excuse me for jumping on this late, but I am excited to weigh in. Unless one is quite familiar with those particular books, it is difficult to speak to their individual accuracy; nevertheless, I can give some general information regarding how textbooks reflect current cultural norms and sometimes ignore historical narratives. I will use the example of my own studies (Holocaust in textbooks) with a particular look at the depiction of victims.

First, textbooks are written by a number of people even though only a few, or sometimes only one, author is given. In fact, for some books, the "author" is actually deceased. Previous editions of the book, which that author did help produce, are simply updated with new information and design. In this way, textbook narratives are prone to maintaining some ways of looking at the past which are no longer recognized as viable and sometimes contain information demonstrated to be inaccurate. Hence, the first problem with textbooks is their reliance on previous textbooks rather than on professional histories.

Regarding the specifics of Holocaust victims in textbooks, my favorite examples for comparison are those of clergy and communists.

In World History textbooks of the 1950s, and, oddly, in books produced in the mid-1970s, clergy were often included as victims of Nazi persecutions. This is not inaccurate as there were clergy, both Catholic and Protestant, who were placed into concentration camps. However, The Pageant of World History said, "The Nazis persecuted Protestants and Catholics as well as the Jews." In this way, the persecution of the Jews and the clergy is equalized. They were, seemingly, persecuted in the same ways, for the same reasons, and to the same degree. Hence the statement is accurate, but the likely understanding of the statement is inaccurate. A more accurate statement would be that clergy were often persecuted as political prisoners when they opposed some Nazi policies regarding the Church in Germany and Jews were persecuted and exterminated simply for their "racial" status as Jews. Hence, victims of Nazi persecution were victimized for a variety of reasons.

Another way in which textbooks struggled to maintain accuracy was in depictions of communists as victims. Early textbooks often noted that communists were arrested by the Nazis and placed in camps. These depictions were often quite accurate and sufficient, although sometimes they suffered from the same problems as the statements regarding the clergy. However, by the 1960s, mention of the communists as victims almost completely dropped off. In fact, textbooks began to suggest, in a roundabout way, that communists were perpetrators. First, communists were taken from lists of victims. This was done during the first contentious years of the Cold War while HUAC (House Un-American Affairs Committee) was doing its investigations; hence, American political culture did not accept communists being depicted as victims. The second step was in speaking of Totalitarianism while discussing the Holocaust. By 1968, the author of The Shaping of Western Society described the Holocaust as related to "Communists and Fascists [who] have rejected democratic institutions" and stated that totalitarians were responsible for the concentration camps, gulags, and genocides. One can clearly see how the anti-communist culture and Cold War mentality influenced the depiction of victimization in the Holocaust. While later textbooks began to include communists as victims again, the textbooks of the 1950s, 1960s, and early 1970s demonstrate a clear trend.

These two examples show how a textbook can both maintain accuracy while giving meaning to an event that does not line up with current historical understanding of that event.

Sources

Leinwand, Gerald. The Pageant of World History. Boston: Allyn and Bacon, 1977.

Good, John M. The Shaping of Western Society: An Inquiry Approach. New York: Holt, Rinehart and Winston, Inc., 1968.