Barack is a Semitic word meaning "to bless" as a verb or "blessing" as a noun. In its Hebrew form, barak, it is found all through the Bible. It first occurs in Genesis 1:22 -- "And God blessed (ḇāreḵə) them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth."
Here is a list of how many times barak appears in each book of the Bible.
Now let us take the name "Hussein." It is from the Semitic word hasan, meaning "good" or "handsome." Husayn is the diminutive, affectionate form.
Barack Obama's middle name is in honor of his grandfather, Hussein, a secular resident of Nairobi, Kenya. Americans may think of Saddam Hussein when they hear the name, but that is like thinking of Stalin when you hear the name Joseph. There have been lots of Husseins in history, from the grandson of the prophet Mohammed, a hero who touched the historian Gibbon, to King Hussein of Jordan, one of America's most steadfast allies in the 20th century. The author of the beloved American novel "The Kite Runner" is Khaled Hosseini.
But in Obama's case, it is just a reference to his grandfather.
Knowledge is strength. Please pay attention in class from now on! :)