Decide if the following sentence is grammatically correct or incorrect.
cuando estaba en la escuela no comía mucho.

You are Correct, It depends n the country Though, Some would add "Cuando estaba en la escuela yo no comia mucho." But overall, Your good.

Explanation:

when you are going to explain a procedure,   the first thing to do is to name the parts or the apparatus you are going to describe in terms of how it or they function. also it is important to know who is going to operate it and the abilities this man/woman requires to manage it.

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