There is an odd bug in the way excel graphs interact with the speed grader.  Students have an assignment where they are to graph data in excel, fit a trendline, and include the equation of the line on their graph.  For several students, when they copied the graph into a word document and uploaded, the equation of the line would not show up in the speed grader but would show up if you actually downloaded the document.  Fortunately a student asked about it, so I knew to check the others - there was no other indication that formatting was messed up.  Any idea what causes this?