Questions about the Images you want to use:
WHO owns the image? Unless YOU photographed/painted/drew/etc. it, it is extremely likely that someone else owns it (and it's not always easy to tell). Images don't have to have a copyright symbol to be under copyright, and just because you can download it, it doesn't mean you can legally use it If someone else owns it, the law says you MUST have their permission (usually for a fee) to use it in most cases.
HOW do you want to use the image? If you want to use it exactly as it is (a full image, meant to be looked at as a picture of what it is) that's one thing, BUT if you want to use it as a part of something else (a mash-up or collage; as part of a video or broadcast, etc.), the rules can change.
WHO is going to see it, and WHERE will they see it? If the project you are using the image in will ONLY be seen by you, or the teacher of a specific course and the students in that course, you're probably okay to use what ever images you want. You should still be giving attribution/credit to the creator/owner of the image and citing the image.
...However, if you plan on uploading the project anywhere beyond your class Canvas page, playing it for the whole school, or broadcasting it via JCTV, you need to find images that you have legal permission to use.
WHY does it have to be this image? With some extra work and digging, you may be able to find something that also meets your need (SEE "What is the Creative Commons" or the other links on this page). If there's a very good reason why it must be that particular image (you are analyzing it or providing commentary on it) your use might be Fair Use. (SEE "What is Fair Use" on this guide)
HOW much work are you willing to do, and HOW much are you willing to spend, to use the image? If you absolutely MUST use that copyrighted image for a broadcast or project, and it's not Fair Use, there are legal ways to acquire license/rights to use images. But they take time, require effort, and likely cost money. (SEE "Acquiring Rights")
Public Domain Images : no attribution needed
Creative Commons Images - remember to check what license covers the image and give attribution!
Images with Various Usage Rights