As I'm on a short hiatus from the world of EduTouring, I'm doing a spot of supply teaching again.
Last week a girl in the 2nd set in Y11 asked me "Why isn't water in the periodic table?"
That's the periodic table of the elements!!!!!
These people will be doing vital jobs in the not too distant future. Save us....
menhir

Methinks by 5th year secondary, the science teaching has been discontinuous; that would not be hard to understand as science teachers are in short supply, we are told.
On the other hand, we don't know what continuity has been like either in teaching, the level of teaching that should have been reached, nor in the student's own education. I assume she could read and write, so that's a good start.
Sadly, like a lot of my generation and the following ones, I am scientifically illiterate; it was a subject that was not on offer in any great quality or quantity in state schooling. That fact alone did not make me a useless member of society, in my view the opposite. It made people like me more gullible to single issue group propaganda. I am glad there is now a concerted effort to address that state of affairs. It may not be perfect, but it is better than what has been before.
One subject alone does not write off an individual. I am delighted she had the confidence to ask the question, it gave you the opportunity to put things right.