Going places
Depending on the duration / permanence of the journey you have two prepositions available. It is hard to decide when to use each one as the temporaryness and permanence of the journey is subjective.
Preposition - a
The a preposition is used for temporary journeys.
- going to your house to pick up a book and then come back later can be considered temporary, but going to your house for the night and coming back to school tomorrow can be considered permanent.
- going on holiday to Spain for a week can be considered temporary, but going to Spain to live for 3 months can be considered permanent.
Preposition - para
The para preposition is used for permanent journeys.
tip
I remember the difference because a is a short preposition (one letter) and para is a long preposition (4 letters). a = short journey and para = long journey.