If (= when) our children are doing their homework, my husband and I always try to be quiet.

[sitifan]

If our children are doing their homework, my husband and I always try to be quiet.
(quoted from A Dictionary of Answers to Common Questions in English, by Zhao Zhencai)
Is the quoted sentence acceptable to native speakers?

 

[Tarheel]

It's common enough.

 

[jutfrank]

Yes, it's fine. Why do you suspect it isn't?

 

[sitifan]

Yes, it's fine. Why do you suspect it isn't?

We use if to introduce a possible or unreal situation or condition. We use when to refer to the time of a future situation or condition that we are certain of:
You can only go in if you’ve got your ticket.
When I’m older, I’d love to be a dancer.
https://dictionary.cambridge.org/zht/語法/英式語法/if-or-when

 

[Tarheel]

I wouldn't have phrased it that way, but maybe I'm pickier than most. Perhaps:

When the kids are doing their homework we're quiet so they can concentrate on their studies.

 

[5jj]

We use if to introduce a possible or unreal situation or condition.

We use 'if' in far more situations than those.