I am a teacher, and i often have a child in my class who has a croupy cough. is it very contagious?

Nutritional: I had a child with repeated episodes of life threatening croup who responded to administration of vitamin b1. This is because the nervous mechanism to the vocal chords is compromised. Vitamin b1 is very common because of all the sugar that kids are taking. Sugar is to gas in a car to the quality of vitamin b1 is to the spark plug. It sounds strange because we always think that croup is infection.