In the lab today. Expected graph - linear. What the student got - near perfect linear. Was surprised because students usually goof up in this experiment, and this particular student often goes wrong. And then I look closely. No scaling, his readings are directly written on the axes. And after that it was madness because he's done that all his life, and was never corrected. Probably the blunder has gone unnoticed.
Not shocking though, because our standards of teaching and learning has gone worse.