Berangkat is usually used only to imply that you are leaving from a certain place to another, while pergi can be used for other meanings, such as "pergi dari hidupku" (go away from my life) and "dia sudah pergi" (he is gone/he passed away) -cmiiw
The choices in the suggested boxes for "going to" did not include "pergi". I chose "berangkat" because it came closest in meaning to "going". Does that mean that "(ber?)pergi" and "berangkat" are synonyms?
I would have thought that berangkat is not the best answer as it implies the I am leaving school, whereas the translation asks for me, going to school. The implication being that i was not at school in the first instance.