During his Internet research, Charles found three articles that eloquently made the points he wanted to make in his speech about gay marriage and the Bible. Charles used portions of each article to make an effective, persuasive appeal that he presented as his own in a classroom speech. Should Charles be concerned about using the work of others without citing the source?

Yes

Explanation:    

Plagiarism is the wrongful activity in which a person tends to extract information from someone else's work and present it as their own.It is type of copying practice in which credit to the original content or source owner is not given .

According to the question,Charles should be worried for carrying out plagiarized act by taking information portions from other's source through internet and then passing it off in  classroom speech as its own. It would be impacting his  credibility and reliability as spokesperson as well as individual because of committing illegal act.

answer; affirm trail court findings of fact;