As opposed to the previous Kudoz link given, I wouldn't translate "sperimentale" as "experimental". Traditionally kids have had to choose what type of high school to attend (classics, languages, science, art...), whereas "sperimentale" appears to be an ""innovative" approach where students are offered a combination of subjects, like UK comprehensive schools, or I suppose US high schools.

Not easy to translate, because it's a different system to those used in the UK and US, but my suggestion may be of some help.

"Allora il nome della scuola era Istituto Magistrale G.Marchi, io ho frequentato la sezione Liceo linguistico sperimentale, sperimentale non per la possibilità di cambiare indirizzo ma perché era sia linguistico che scientifico insieme."

See this discussion:
https://forum.wordreference.com/threads/liceo-linguistico-sp...