I absolutely agree with you; I don't understand why the author claims what he does.
i.) p--> q is false
ii.) p is true.
The book says that it cannot be concluded whether or not you can change your grade. It seems to me that it can be it can be concluded that q is false. We know that p is true and p-->q is false; it can be concluded that q is false because p-->q is false only when p is true and q is false.
I believe that whether this example applies depends on what the topic the book is teaching. If the topic is the context of reasoning, e.g., adding new, previously hidden, propositions that may change the truth value of the old ones, then yes, the example is relevant. However, if the topic teaches regular propositional logic and regular rules of inference, it is probably a stretch.
Say every Monday when you can access the network, you can change your grade, but only on Monday. So accessing the network is not sufficient for changing your grade, meaning (p -> q) is false. But suppose you have access to the network on all days, meaning p is true. Now given all these facts, we cannot conclude whether q is true, because we don't know what day of the week it is.