@happybro: most working adult don't have the math skill (nor physics, chemistry, biology...) of a high schooler - they already forget it. If you give random adults some simple sin-cos problems, you will see their face slowly turn pale. Meanwhile, the skill that these working adult know - IT, e-marketing (without computer or internet), logistics (without plane and the mean to preserve goods over long distance), advanced engineering (without modern machine and material),.. make no sense in this world. Thus, useless.
On the other hand, the MC are clueless about this world, about its geography, history, culture, biology, physics (law of Conservation of Energy stop making sense when you can create a fireball [energy+mass] out of nowhere),... He doesn't have any developed ability - can't fly, can't breath fire, and his body is squishy as hell. Totally helpless. If i was his teacher, i would treat him just like how he is treated by the lamia teacher - a remarkable kid (like the kid that could speak 3 languages, or could play the violin really well) but nevertheless, a helpless kid with a lot to learn.