Rewrite sentence using commas.

As they studied the film they noticed some rules of science at work.

I wrote...
As they studied the film, they noticed some rules of science at work.
There isn't one after noticed - right?

You're right.

Thank you

Your rewrite of the sentence is correct. Adding a comma after "film" in the sentence "As they studied the film, they noticed some rules of science at work" is appropriate. The comma is used to separate the introductory clause "As they studied the film" from the main clause "they noticed some rules of science at work." This helps to improve clarity and readability by indicating the natural pause in the sentence. Additionally, there isn't a need for a comma after "noticed," as there are no additional clauses or phrases following it.