use of in/at classess.

[Hardwork]

Hi please help me with these sentences grammatically.
She is always at/in calsses.(guitar classess)

I was in/at classes when she called me.

I going to get a new room (I mean we are construting new room so that going to be my new room so is this the right way to say it.)

[Esl_Expert]

Hi Hardwork

For your first sentence, I would use 'in classes'.

I would word your second sentence this way:
- I was in class when she called me.

As regards your third sentence, yes, that is one way you could say that. However, it does not necessarily mean that a new or additional room is being constructed. It simply means that you will be moving from one room (the 'old' one) to a different room (the 'new' one).
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