Pero castellano (o, más probablemente, español) es el idioma que la mayoría de los estudiantes aprendieron cuando yo estuve en escuela.
But I have to admit, though I could read what y'all have been writing, I had to look through review texts and a dictionary to compose my answer. And then check it on Google Translate. When did "estuve" get replaced by estaba, which is what Google kept giving me?