Is this sentence grammatically correct? (English)?

Question

I'm grading my students' English composition test right now and I found one answer seemed to be grammatically wrong!
So I deducted her points but she claims that her sentence is just less common expression - not grammatically incorrect.

Below is her sentence:
"In fact, the average child spends more than four hours in front of a screen each day, engaging in screen entertainment, substituing time that used to be spent for physical activity."

I personally think there should be an 'and' between 'entertainment' and substituiting'.
Also 'that used to be spent FOR physical activity' is what she wrote, but shouldn't it be 'spent ON physical activity'?

I'm just an undergrad student and grading high schoolers' test is my part time job (which means I'm not professional)!
So I might be wrong and her answer might be correct.

If you are a native speaker of English and quite confident in English grammar, please tell me if her answer is correct or not.

If you think her answer is grammatically incorrect, please explain why so that I can convince her.

Answer 1

I think that the only reason it might be incorrect is that there shouldn't be a comma between "each day" and "engaging in".
However, I do agree with saying "on physical activity" rather than "for".
The sentence should be:
"In fact, the average child spends more than four hours in front of a screen each day engaging in screen entertainment, substituting time that used to be spent on physical activity."

It could be better if the extra "screen" was ommitted:
"In fact, the average child spends more than four hours each day engaging in screen entertainment, substituting time that used to be spent on physical activity."


I'm no teacher or professional, but that's what I think it should be.

Answer 2

The sentence lacks flow. When constructing a sentence, you must take into account the use of grammar, vocabulary, AND mechanisms. It should be reworded.

"In fact, the average child spends more than four hours each day in front of a screen for the sole purpose of entertainment, substituting time that used to be spent on physical activity."

The student wants to stress the amount of time used on entertainment in a day. Keep the units of time together and add "for the sole purpose of entertainment" so that the time AND use of time is emphasized... therefore further elaborating the emphasis on what the time was once used for in the past on the next part of the sentence.

Answer 3

Without the comma after "day" it would be a perfect sentence.

"In fact, the average child spends more than four hours in front of a screen each day engaging in screen entertainment, substituting time that used to be spent for physical activity."

Comment on her repetition of the word "screen" though, and also, ask her to further elaborate on how the average child "used to be spent for physical activity" unless it is explained in the paragraph.

Answer 4

There are a lot of answers here, but I think only a few of them brush on the core problem. You asked if the sentence is correct English, and it is. That is not the issue though. The issue is whether the sentence makes sense in the context of the presentation that they were giving. No one can answer that without first knowing the context. Several of the above answers allude to the different meanings. You could then deduce what they were intending, but we cannot actually tell you if the sentence made sense in the context without seeing more.

Answer 5

My suggestion: "...in front of a screen every day, engaging in "on-screen" activities, and thus not engaging in physical activities as children used to do."

I have not bothered to analyse your idea grammatically, since, as you will note from my suggestion, your idea is simply not "normal English usage" and any minor tinkering to make the grammar correct would still end up with a version which was distinctly "foreigner's English".

Answer 6

Yes, it actually is a grammatically correct sentence. It's called a cumulative sentence. As long as it's not a complete sentence after the comma, you can add on as many clauses linked by only commas as you want.

Answer 7

The phrase beginning with "substituting" is called a free modifier; it refers to the phrase before it. No "and" is required before it.

And I agree, it should be "on," or even "in."

I have a problem with the word "substituting;" it would seem to need a "for" in the sentence. I might use "replacing" or "supplanting."

Answer 8

This appears to me to be an issue of semi-colons. The sentence works, as written, if two semi-colons are used:

1) ...each day; engaging...
2) ...entertainment; sbustituting...

Best wishes.

Answer 9

No her answer is incorrect.