On Friday, MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) hosted 150 local high school students for its second annual "Hour of Code" event, tied to the international initiative focused on getting kids interested in programming. Researchers showed off robots, 3-D-printing technology, and other projects to math and computer science students from schools throughout the greater Boston area, including Cambridge, Charlestown, Roxbury, and Somerville. The event also included a surprise video message from John Green, author of the bestselling young-adult novels-turned-movies "The Fault In Our Stars" and "Papertowns." Green commended the students on participating the event and elaborated on why coding is important. "I cannot emphasize enough how much I believe in learning computer science, not least because I am basically a first-grader when it comes to computer literacy," Green said.