Why is я была в школе в это время wrong?
it's not, report next time
Could one use эта время or does that have a different meaning?
No, because время is neuter. (I know this is from years ago, but other users could have the same doubt.)
I used В это время я было в школе and was corrected with В это время я была в школе. Is there a reason I can't use было here?
You use я был if you are male and я была if you are female, было is neuter.
What is the difference between В это время and тогда?
The literal translation (which is what Duolingo is asking) is "at that time" and "then". The meaning is the same however.
What's wrong with В то время я был на школе?
На школе probably means something like "on the school".
both correct I think
Why это and not этом
''В'' can be either prepositional or accusative and you have to remember which one it is in which case. In this case it is apparently accusative. время belongs to a small group of words that are neuter gender -> accusative form = nominative form
But why is it В + Acc. I thought this was just for movement towards.
why была and not был? There is no indication as to the gender of the speaker.
Both are correct here.