Edit: First, I am not a lawyer but I spoke with my professional photographer friends, one is also a photo teacher and they said it is legal (USA) to use images for educational purposes (or personal use) ie NOT for profit. It is considered “fair use.”
Yes, attribute the photo but it is not legally required in an educational setting or for personal use. It’s not a legal problem. You might have a personal moral problem with unattributed images on a Tribute Page but it is not a legal problem.
@astv99 Yes, I read the posts, can I ask questions? Are you a lawyer? Turns out I am correct. @genestd was getting stuck locating images- " I have found a few pics I could directly link to, but most are low quality. Any better suggestions out there?" In a professional environment (for profit) it is a serious issue but that is different from an educational environment (not for profit) it’s not a legal problem.
My point is; I won’t let using web images stop me from completing a challenge. It is legal in the USA in an educational setting like FCC.