I am with dbello, I teach American History and I have never taught that the Empancipation Proclamation freed slaves. But I also can see how this can be confusing, and it might be covered in a such a general way that students can interpret it as a law that freed the slaves. It is very important for teachers to very clear when there are teaching about this law, otherwise they will be teaching false history.
I teach U.S.history and have never taught the Emancipation Proclamation 'freed' the slaves. Fortunately I have never come across that misinterpretation in my school, however I understand the purpose of your question. The fact was the Confederates had won more battles than the Union between 1861-1862 and President Lincoln had contemplated a speech to be delievered after a union victory. The speech would serve as a morale booster for the north, as well as adding a moral footnote to the war. Make no mistake regarding Lincoln's intent, although he viewed slavery as evil, his primary concern was keeping the Union together. Secondly, but just as important, Lincoln's Emancipation had no legal bearing upon anything. The Emancipation Proclamation is enlightening and moving, however it was a speech, not LAW. According to the Constitution the only branch of government that had the power to abolish slavery through a Constitutional Amendment was The Congress...Unfortunately, if The Emancipation Proclamation is misinterpreted or misunderstood and being taught the way your topic suggests, students will not have the chance to develop a clear perception of the history. My advise to all history teachers is to dig into your subject matter. Understand it from the inside out. I realize that this takes much time and dedication, however the alternative undermines everything that a teacher is......
"In September of 1862, after the Union's victory at Antietam, Lincoln issued a preliminary decree stating that, unless the rebellious states returned to the Union by January 1, freedom would be granted to slaves within those states. The decree also left room for a plan of compensated emancipation. No Confederate states took the offer, and on January 1 Lincoln presented the Emancipation Proclamation. The proclamation declared, "all persons held as slaves within any States, or designated part of the State, the people whereof shall be in rebellion against the United States, shall be then, thenceforward, and forever free."
This is what many teachers teach, what they seem to always overlook is that all the slaves were not freed. The only slaves that received their "freedom" were the slaves in the confederate states. Any state still in the Union was allowed to keep their slaves.
Lincoln originally wanted to free the slaves on a gradual basis and compensate the "owners for their property." He could not get any support for this idea. Lincoln finally gave the "Confederate states" an ultimatum to rejoin the union or lose their slaves. None of the Confederate states rejoined thus he freed the slaves in the Confederate states.