Final answer:
The correct sentence that uses italics properly is: We watched the movie The Life of Pi on Saturday night, as movie titles should be italicized.
Step-by-step explanation:
When dealing with the titles of long works such as movies, books, or plays, the correct formatting is to use italics. Short works, like articles, poems, or chapters, are formatted with quotation marks. Therefore, the correct use of italics in the student's question is: We watched the movie The Life of Pi on Saturday night. Remember, titles need to stand out from the regular text, and italics serve this purpose for longer works.