In middle school, children are taught that the Emancipation Proclamation freed the slaves when, in fact, it didn’t free any slaves.

It did, however, have some concequences and it wasn’t a pointless piece of paper (Lincoln knew what he was doing)

1. It changed the purpose of the war. Before the Emancipation Proclamation was passed, the war was about getting the Southern States to rejoin the Union. After the Emancipation Proclamation was passed, the war became focused arounds the issue of slavery.

2. It allowed President Lincoln to allow run-away slaves to join the military and fight against the south. Before the Emancipation Proclamation was passed, there were many run-away slaves in the north. Lincoln couldn’t send them back to the South because he knew they would be beaten and/or killed. He also couldn’t keep them in the North because they were not legally free. Many African Americans tried to enter the military to fight against the South during the Civil War, but Lincoln could not allow them to fight because there was no law saying they were free. After the Emancipation Proclamation was passed, all African Americans in the north were free and, therefore, Lincoln could allow them to fight in the war.

It was widely attacked at the time as freeing only the slaves over which the Union had no power, but in practice, it committed the Union to a war to end slavery, which was controversial in the North. It was not a law, but a presidential order.

The proclamation did not free any slaves in the border states (Kentucky, Missouri, Maryland, Delaware, and West Virginia), nor any southern territory already under Union control. It first affected only those slaves that had already escaped to the Union side, but as the Union armies conquered the Confederacy, thousands of slaves were freed each day until nearly all (estimated at 4 million) were free by July of 1865.

see link for additional (wiki) info

In other words, it freed slaves where it had the weakest authority to do so.