Sentence 1: Ian completed his science report. 
 Sentence 3: When Ian got home, he searched for his flash drive 
 Sentence 4:  He realized that he left it at the library 
 Sentence 5:  Since the school was far, he couldn't go back and restarted the report 
 Option 1: He sent the document to his email as backup. 
 Option 2: He saved the document and left it in the library.