I show my students that cognitive abilities declined significantly with lack of oxygen. I have them do jumping jacks while reciting the alphabet backwards. There is often a 50% decrease in speed when they are working out.
I can recite the reverse alphabet almost as fast as forward without the added stress. While working out I can do it with a10% decrease. This leads me to believe that the additional stress can be compensated through drilling.
That would be one more classroom nightmare for me. The only way I can recite the alphabet is by singing that stupid song I learned in grade school. To do so backward, I would first have to sing forwards until I reached the next 'backwards' token, for each and every letter, so jumping jacks or not it would be at least 50% slower.
Even with the song I sometimes get stuck, but I also have a dyslexic mind and absolute hate any alphabet exercises. I would absolutely hate your class (but not you necessarily) and would spend my time in there counting down the school year to never have to go again.