6.00x students earn credit for submitting code to online checkers. Feedback is instant, but limited: A green checkmark appears if your code passes all test cases, otherwise it lists failed tests. edx.org Feb. 8, 2013 Facebook Twitter Reddit Print 6.00x students earn credit for submitting code to online checkers. Feedback is instant, but limited: A green checkmark appears if your code passes all test cases, otherwise it lists failed tests. edx.org