It was a science test in which dd - usually super-whizz science geek - did rather badly. They were told to go over their papers and correct them for homework.
The question of the difference between vertebrates and invertebrates was the one she had trouble with. She had said vertebrates have a spinal column and spinal chord (I think she was anxious and over-compensating). I couldn't really remember and googled, as did she, but we didn't find anything that we felt utterly confident about. So, of course I turn to MN, knowing that someone (at least one!) will come and tell me exactly what she needed to know.