Arrive with something you cannot say yet. A partner session with no material becomes an exchange of the questions both of you can already handle, and two people can run that arrangement weekly for a year while getting steadily more comfortable and not at all better.
What to bring is small and specific: one subject you have never discussed in this language, and three sentences you tried to produce during the week and could not finish. That is fifteen minutes of genuinely hard talking, which is more than most sessions contain.
Eight rules that make an exchange survive
- split the time strictly, with a timer. Without one, the exchange drifts into whichever language is easier for both, which is usually English.
- half in each language, switching at a fixed point rather than when it feels natural.
- expect to drift into English. Naming this at the start and agreeing on a signal is what prevents it.
- agree on correction in advance: everything, only what blocks meaning, or nothing. Mismatched expectations end more exchanges than anything else.
- a partner is not a tutor. They will not know why something is wrong, only that it is, and that is still valuable.
- bring a topic. Unstructured conversation between two strangers in two languages runs out in fifteen minutes.
- meet weekly at a fixed time. Exchanges that are rescheduled twice usually stop.
- two partners is more reliable than one, because one will always become busy, and the habit survives if the other remains.
A partner is not a teacher, and that is useful
Somebody who is not trained cannot usually tell you why a sentence is wrong, and asking them to is how a partner session turns into a bad lesson. What they can do, better than most teachers, is tell you whether anybody says that.
That is a different signal and it is under-supplied. A teacher answers the question you asked, about a rule; a partner reacts to a sentence, and a slight hesitation before they answer is information you will not get anywhere else. Use them for the does-anybody-say-that question and save the why for somebody who is paid to know.
It also means the correction rule has to be agreed out loud at the start, because an untrained partner's default is to say nothing. Ask for one thing: interrupt me when you do not understand, and tell me afterwards what sounded odd.
Where it stops: the session with nothing in it
The stall is a comfortable hour. Two people who like each other, a familiar set of subjects, and a conversation that goes well every single week. Neither of them is doing anything wrong and neither is being stretched.
It persists because the feedback is good. A session that felt easy felt successful, both parties leave satisfied, and the arrangement is pleasant enough to survive for a year, which is the length of time in which nothing measurable happens.
The signal to watch for is your own comfort. If you did not reach for something you failed to say, the hour was social, and social is worth having and is not what this was for.
Finding somebody in the first place
The language exchange subreddit on Reddit is free, needs no more than an account, and is one of the few places where people post looking for a specific pairing rather than joining a general pool. Post what you have and what you want, in both languages, and say when you are available.
It replaced a noticeboard in a university language department, which reached the people already in that building and nobody else.
Two limitations. Nothing is moderated for quality, so a first exchange with a stranger is a lottery and worth treating as one, and most posts get no reply at all, so this is a numbers game rather than a search. Expect to write five and hear from one.
What it looks like when it goes wrong
The recognisable failure is an exchange conducted entirely in whichever language is easier for both of you. It happens gradually, nobody decides it, and by the third month the arrangement is a friendship with a language attached rather than practice.
The second is the unequal hour, where the person with the stronger second language carries both halves because it is quicker. It is generous, it is invisible while it is happening, and the generous one gets nothing.
Why a correction only does anything when it lands inside an attempt you were already making is finding someone to speak to, and what to do in the hour, and what somebody paid can do that a partner cannot is what a teacher is worth, and what you can do alone.
The open question is what happens between sessions, because an hour a week is a small object and everything that makes it worth anything happens in the other six days: turning a vague intention into hours on a calendar.