'in certain schools' is correct and usable in written English.
You can use it when referring to specific schools that have been mentioned in the context of a sentence. For example: "Students in certain schools must wear uniforms to class."
Does this signal a national problem or, rather, bad practice in certain schools?
According to the report, this influx was concentrated in certain schools and communities.
In online learning, these initial areas can include advanced-placement courses that aren't available in certain schools.
We compare the search account with poststructuralist accounts of the accidental move, which we argue have greater currency in certain schools of thinking about design.
Examples include programmes to improve standards of nutrition in certain schools and to finance co-operatives working on public infrastructure projects.
"Historically, the idea was that only certain kids in certain schools should get advanced work," said Lee Jones, the College Board's director of the Advanced Placement program.
Hell, I could even see them subsidizing Chrome notebook costs to get them available to all students in certain school districts that commit to Google Apps.
I excelled in certain school subjects.
This is an effective way to earn money and works really well if you are excellent in certain school subjects such as mathematics and language.
Yet Ms. Moskowitz and others who study the school system joined parents in wondering why certain schools were not included.
We cannot interpret why students in a certain school programs manifest significantly in factors, such as, initiative and acquiring skills.
