You can always click 'Scoring' at the top of the Detailed Report within any Assignment Report to see a key of what each color and symbol means.
Green indicates the student was correct on their first attempt. Orange indicates the student was correct after 2 or more attempts. Red indicates that the student had to view an explanation or click 'Show Answer' in order to move on to the next problem.
X's indicate the number of incorrect attempts on each problem. Triangles indicate whether the student viewed a hint prior to answering correctly.
Click here to learn more about how to interpret the Assignment Report.