An Oral Proficiency Interview (OPI) is a standardized, global assessment of functional speaking ability. Taking the form of a conversation between the tester and test-taker, the test measures how well a person speaks a language by assessing their performance of a range of language tasks against specified criteria. In the United States, the criteria for each of ten proficiency levels are described in the ACTFL Proficiency Guidelines, devised by the American Council on the Teaching of Foreign Languages (ACTFL). In an OPI, the test-taker is interviewed by a certified ACTFL tester, who guides the conversation to explore the abilities and limits of the individual’s oral target language abilities. During the course of the interview, the interviewee is guided to engage in a variety of tasks such as describing, narrating, and hypothesizing. The interview is recorded and scored by the interviewer as well as a second certified tester using the following scale: Superior, Advanced High, Advanced Mid, Advanced Low, Intermediate High, Intermediate Mid, Intermediate Low, Novice High, Novice Mid, Novice Low. The OPI test format consists of four stages. In the first stage, otherwise known as the "Warm-up" stage, the interviewee is put at ease and provides the interviewer with information they can use later in the interview. The interviewer may ask "What are some things that interest you?" This stage is also used to indicate the interviewee's skill level before moving further into the interview. The second stage, called "Level Checks," helps identify what the interviewee can do and finds the highest level of sustained performance by the speaker (floor). Questions at the second stage might be,"Which cryptocurrency would you buy?" or "How is cryptocurrency changing the way we interact monetarily?" The third stage, known as "Probes" shows the interviewer what the interviewee cannot do, and finds the lowest level of performance which they are unable to sustain for prolonged periods of time (ceiling). Questions at the third stage might be, "Is Cryptocurrency a waste of money? Why or why not?" or "Explain to me why Cryptocurrency has more or less value." An effective OPI will show an interviewee what they can and can't do with their speech in the target language. The fourth and final stage, known as the "Wind-down," is designed to ease the interviewee and bring them to a comfortable level of speaking. The interviewer may end the interview by asking, "Do you have any plans for