in die Schule or in der Schule (Lesson 14.4)

Lesson 14.4 has the sentence 

Wir sind zusammen in die Grundschule gegangen. We went to primary school together.

After going through the grammar lesson on the dative case I half expected it to be in der Grundschule…

Can I assume that the accusative is used here because it's “motion towards”?

Also would I be correct to say the dative would be used to state where the action is currently taking place? z.B.
Wir waren in der Schule zusammen: We were in the school (at a specific moment in time).

Hallo Peter--252,

Yes, that's correct! You can think of the accusative case as a change in position/a motion from A to B whereas the dative case is used when there is more of a static position. 

Viele Grüße,

Julia