The Passover- Liberation

Do to migration and high birthing rates, Egypt was very overpopulated a long long time ago. In order to decrease the population in Egypt, the Pharaoh came up with a plague and he would kill the first born son of every family. The only way to save your son was to slaughter a lamb and use its blood to paint the front door. Then you had to roast the lamb and eat it. God would "pass over" the homes that had blood on the doors, and the holiday Passover was created. 

(http://wp.patheos.com.s3.amazonaws.com/blogs/faithwalkers/files/2013/03/passover-lamb.jpg)

Here is a paining of a man rubbing the blood of a lamb onto his front door so that the Pharaoh will not take his son as a sacrifice during the plague. 

To be honest, I'm not sure how this has to deal with liberation. Liberation is the act of setting someone free from imprisonment, slavery, or oppression. I guess killing the lamb liberates the first born son from being sacrificed. His life would no longer be in the control of the Pharaoh, but rather his own family and self. This would also liberate the parents from fear. Instead of fearing that their child will be taken from them, they can rest easy knowing they sacrificed a lamb instead.