As the costs of graduate education skyrocket and students demand cheaper, more-convenient ways of learning, colleges and universities are increasingly experimenting with so-called "stackable degrees." Think Lego blocks of college education, letting students start with a MOOC, then add a few more MOOCs to get an online certificate, then add yet more courses to get a traditional master’s degree. The University of Illinois at Urbana-Champaign announced such a degree on Wednesday. Starting this fall, students can enroll in an online master’s degree in data science, offered in conjunction with Coursera, the for-profit platform that produces massive open online courses.