Learn German: Dann sind wir sofort aufgestanden.

aufgestanden comes from the separable verb aufstehen (to get up). For separable verbs in the Perfekt tense, the -ge- gets sandwiched between the prefix (auf-) and the rest of the verb (-standen).

Wait, why is the base part -standen instead of -steht?

stehen (to stand) is an irregular verb. Instead of taking the regular -t ending in the past participle, it changes its vowel and ends in -en, becoming gestanden. Add the prefix back on, and you get aufgestanden.

The English translation says 'we got up', but the German uses sind (are). Why not haben (have)?

In German, the Perfekt tense uses sein (to be) as the helping verb for verbs that express traveling, movement, or a change of state. Getting up out of bed is a change of state, so aufstehen uses sein. That is why we say wir sind ... aufgestanden.

Why does the verb sind come before the subject wir?

German statements have a strict rule: the conjugated verb must always be in the second position. Because this sentence starts with the word Dann (Then) in position one, the verb sind must take position two. The subject wir simply gets pushed to position three.