Translation seems only part of the sentence

Question

Why does the first sentence " - Sophie, when you were in sixth form [US: high school]," translate to - Sophie, quand tu étais au lycée - there is no mention of the "sixth form".

Maarten Kamp · Accepted Answer

Dragana, 
there is no direct French translation of ‘ sixth form ‘ as a period of education. 
It is not even a term used in my part of the English speaking world, or in the US apparently, given the clue.
A search gives the description of “ sixth form “ in the UK as ‘ the final 2 years of secondary education ‘, usually between 16-18 years of age. 
https://britannia-study.com.my/guides/uk-sixth-form
The closest to an equivalent educational stage and age of students in France is ‘ le lycée ‘ ( ‘ première ‘ and ‘ terminale ‘  years of ‘ lycée ’ especially ), hence the translation used. 
 
https://en.wikipedia.org/wiki/Secondary_education_in_France