間 vs 時 vs うち to refer to time intervals

Question

So I was considering the grammar points 間に, うちに and 時に today. I came across this question, which talks about 間に vs うちに (which was already in my grammar book).

I'm more curious about the differences between 時に and these constructs. Specifically, today I wanted to make the sentence "I often make mistakes when I write essays". I wrote

作文を書いている時よく間違いをする

What happens if I write

作文を書いている間によく間違いをする

作文を書いている内によく間違いをする

My current best guess is 時 indicates a general point of time, whereas 間 and 内 represent a specific interval, so 時 is more natural here.

Any ideas? My grammar book describes the difference between 間 and うち, but not how it relates to 時.

Answer 1

作文を書いている時(に)よく間違いをする

When I'm writing an essay, I often make mistakes.

• 時 refers to a point in time, the point in time where you're writing.
• に is optional

Using 時 means that the action took place right after, right before, or exactly at that time. In this case, it means 'right after' because you cannot make a mistake before you start writing: context will tell you.

作文を書いている間によく間違いをする

While I'm writing an essay, I often make mistakes.

• 間 refers to a span of time, the duration of writing.
• に is not optional.

If に is used, it can have two meanings depending on the verb of the main clause. If it's a punctual verb, as in this case 間違いをする, the action took place instantly at some point in the span of time marked by 間.

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In summary, in this case, both sentences mean the same thing, but 時 focuses on a point in time, whereas 間 a span of time, hence the translation:

• When this happens, something often comes true.

Here, 'happens' refers to the point of time where you're writing.

• While this is happening, something often comes true.

'this is happening' refers to a span of time.

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作文を書いている内によく間違いをする

While I'm writing an essay, I often make mistakes.

• に is a must

This sounds as if making a mistake, while you're writing, is beneficial because of 内に.