Learning how to use Wa / ni / ga

Question

Is this right like this?

Children are at school: Kodomo tachi wa gakkou ni imasu.

There are children at school: Gakkou ni kodomo tachi ga imasu.

Thank you

Answer 1

Yes, both sentences are grammatically correct.

For the difference between wa and ga, please read this: What's the difference between wa (は) and ga (が)? In your first example, everyone in the conversation knows who those "kodomo tachi" are. Maybe they are their own children. In your second example, you are introducing "kodomo tachi" into the discourse with this sentence.