Obviously neither of you do photography or graphic design for a living then. The people that create those copyrighted images often do it as a job. Using them without paying is theft. Posted via Mobile Device
You were the one who initially implied that if it was on google it was free for all. Not the case. Something you would have a better understanding of if you were aimed toward either profession. Posted via Mobile Device
I understand you may think since it was on google you may freely use it but HowClever is right. You can get into BIG trouble for using that sort of thing without either paying for it or saying who is responsible for it, depending on what you allowed to do with picture,information etc.
That is why with assignments and such you have to have a bibliography and reference otherwise you are STEALING. I heard of a guy who did a huge speech in uni with a big media presentation. He ended up failing it, being removed from the course he was doing and having a huge lawsuit against him because he forgot to reference a short videoclip he used that wasn't his. Trust me there can be big concequences.
No you can only use things that are marked as free use (such as stock photos on DA). Just becuase there isn't a blatant copyright on the image does not mean that it is free for anyone to use.
I really, really am not trying to attack or be mean here. Copyright/art theft is never a good thing. Trust me. I have had art ripped off and I do not want to have it happen again to me or anyone else for that matter.
You really (and I can't stress this enough) need to make sure that the pictures you are using are free for you to use. Heck even the ones on DA have rules on where they can and can't be used.