1. What school do you go to?

2. What school do you attend?
3. Where do you go for middle school?
- I go to London Middle School.

[Which questions are correct and commonly used?]

All are commonly used.

All three questions are correct and commonly used, but they differ slightly in their wording and emphasis.

1. "What school do you go to?" is a general and straightforward question asking which school someone attends. This question can be used for any level of education, including elementary, middle, or high school.

2. "What school do you attend?" is another common question that can be used for any educational level. This question is slightly more formal and can be used in various contexts, such as when meeting new people or during casual conversations.

3. "Where do you go for middle school?" specifically asks about the middle school level. This question assumes the person being asked is still in middle school or has attended a middle school in the past. It can be used when discussing educational experiences or transitioning between different levels of education.

Ultimately, all three questions serve the same purpose of inquiring about the school someone attends, but their wording and emphasis can vary depending on the context and the level of detail desired.