I teach the English side of 3rd grade at our Portuguese dual-immersion school. I love everything about elementary students learning a second language, particularly in the United States!
My Brazilian partner teacher has a "Portuguese only" rule in her classroom, so when I go across the hall to speak to her or her students, I ought to follow suit. I knew Spanish before I started learning Portuguese and would interrupt her class by saying, "Com permiso." On Duolingo I learned that "com licença" is the proper way to say "excuse me." Though my partner teacher was too nice and never corrected me when I erred, she did notice a change when I fixed my "Portañol." Thanks, Duolingo! :)