Correcting papers

The most unpleasant part of my job are the examinations...invigilating and correcting papers. The first is mind-numbing and the second mind-boggling.
When I correct papers, I wonder what goes on in students' minds. What are their cognitive abilities...
I quote from papers written by second year BSc students to whom I taught physical and general chemistry this year.
" The plane of symmetry contain one water molecules on the perpendicular to plane. The water molecules on both sides." I wonder what it means.
Someone else who taught inorganic chem hasn't fared much better...
"Lanthanide contraction:according to lanthanide contraction, electrons are very much defused"
Good thing I say! ...the darn things might have exploded in our faces! does lanthanide contraction have any other vishesh tippani?
I used to be in charge of conducting and correcting/valuing the answer scripts for a compulsory exam in a subject called "science and civilisation" I used to correct a huge number of these papers every year(about 600). Long ago, when my son was about 13 yrs old, he was sick and I had stayed home to look after him. I had brought home some of these papers to correct. I read out some of the answers...he fell out of his bed laughing.
These papers were a great source of entertainment.