I wouldn't put disingenuousness past them. I've been searching on Horace Mann and it seems that his history has been largely whitewashed. (I found some hard info though, his 10th Address to the Massachusetts Board of Ed. I'll provide exerpts below) But in the case of the history of American education, it's very hard to find hard facts. There are many threads running through its checkered history.
It is impossible for us adequately to conceive the boldness of the measure which aimed at universal education through the establishment of free schools. As a fact, it had no precedent in the world's history; and, as a theory, it could have been refuted and silenced by a more formidable array of argument and experience than was ever marshaled against any other institution of human origin. But time has ratified its soundness. Two centuries of successful operation now proclaim it to be as wise as it was courageous, and as beneficent as it was disinterested. Every community in the civilized world awards it the meed of praise; and states at home and nations abroad, in the order of their intelligence, are copying the bright example. What we call the enlightened nations of Christendom are approaching, by slow degrees, to the moral elevation which our ancestors reached at a single bound."Charity = Duty"? Sounds like something from "Animal Farm."The alleged ground upon which the founders of our free school system proceeded when adopting it did not embrace the whole argument by which it may be defended and sustained. Their insight was better than their reason. They assumed a ground, indeed, satisfactory and convincing to Protestants; but at the shat time only a small portion of Christendom was Protestant, and even now only a minority of it is so. The very ground on which our free schools were founded, therefore, if it were the only one, would have been a reason with more than half of Christendom for their immediate abolition....
...there is not at the present time, with the exception of the States of New England and a few small communities elsewhere, a country or a state in Christendom which maintains a system of free schools for the education of its children....
I believe that this amazing dereliction from duty, especially in our own country, originates more in the false notions which men entertain respecting the nature of their right to property than in any thing else. In the district school meeting, in the town meeting, in legislative halls, everywhere, the advocates for a more generous education could carry their respective audiences with them in behalf of increased privileges for our children, were it not instinctively foreseen that increased privileges must be followed by increased taxation. Against this obstacle, argument falls dead. The rich man who has no children declares that the exaction of a contribution from him to educate the children of his neighbor is an invasion of his rights of property. The man who has reared and educated a family of children denounces it as a double tax when he is called upon to assist in educating the children of others also; or, if he has reared in his own children without educating them, he thinks it peculiarly oppressive to be obliged to do for others what he refrained from doing even for himself. Another, having children, but disdaining to educate them with the common mass, withdraws them from the public school, puts them under what he calls "selecter influences," and then thinks it a grievance to be obliged to support a school which he contemns.[!]...
I believe in the existence of a great, immortal, immutable principle of natural law, or natural ethics,--a principle antecedent to all human institutions, and incapable of being abrogated by any ordinance of man,--a principle of divine origin, clearly legible in the ways of Providence as those ways are manifested in the order of nature and in the history of the race, which proves the absolute right to an education of every human being that comes into the world, and which, of course, proves the correlative duty of every government to see that the means of that education are provided for all...
In regard to the application of this principle of natural law,--that is, in regard to the extent of the education to be provided for all at the public expense,--some difference of opinion may fairly exist under different political organizations; but, under our republican government, it seems clear that the minimum of this education can never be less than such as is sufficient to qualify each citizen for the civil and social duties he will be called to discharge...
...So far is it from being a wrong or a hardship to demand of the possessors of property their respective shares for the prosecution of this divinely ordained work [government schools], that they themselves are guilty of the most far-reaching injustice when they seek to resist or to evade the contribution. The complainers are the wrong-doers. The cry, "Stop thief!" comes from the thief himself....
The three following propositions, then, describe the broad and ever during foundation on which the common school system of Massachusetts reposes:--
1. The successive generations of men, taken collectively, constitute one great commonwealth.
2. The property of this commonwealth is pledged for the education of all its youth, up to such a point as will save them from poverty and vice, and prepare them for the adequate performance of their social and civil duties.
3. The successive holders of this property are trustees, bound to the faithful execution of their trust by the most sacred obligations, and embezzlement and pillage from children and descendants have not less of criminality, and have more of meanness, than the same offences when perpetrated against contemporaries.
For public, free education alone, including the direct outlay of money and the interest on capital invested, Massachusetts expends annually more than a million of dollars. To support religious institutions for the worship of God and the salvation of men, she annually expends more than another million, and what she gives away in the various forms of charity far exceeds a third sum of equal magnitude. She explores the world for new objects of beneficence; and, so deep and common is the feeling which expects and prompts all this that she is gradually changing and ennobling the definition of a cardinal word in the language of morals,--doing what no king or court with all their authority, nor royal academy with all its sages and literary men, can do: she is changing the meaning of charity into duty.