For one group of high school students in Washington, D.C., the first week of classes ended on a high note. Former President Barack Obama made a surprise visit Friday to McKinley Technology High School, strolling ever-so-casually into a classroom to the disbelief of students.

"Hey, how’s it going everybody?” Obama, 56, said to the stunned students, who were seated in a circle with D.C. public schools chancellor Antwan Wilson. "The chancellor told me you guys were meeting, so I thought I’d stop by. How's everybody doing? Is that my seat? You don’t mind me crashing, right?”