You can’t have enough sources for Creative Commons or free images/pictures. To the list, I’d like to suggest that you add Pexels.
Their claim is that they host “Free high quality photos you can use everywhere”. All without attribution to the creator. This is a refreshing approach. After poking around, there are some very good images to use. I did my usual search for “house”.
All photos on Pexels are under the Creative Commons Zero (CC0) license. This means you can copy, modify, distribute and perform the photos. The pictures are free for personal and even for commercial use. All without asking for permission or setting a link to the source. So attribution is not required. All in all the photos are completely free to be used for any legal purpose.
For student purposes, I still think that the first choice should be pictures, images, drawings, screen captures, … that they’ve created themselves but there are times when that’s just not possible.
There isn’t a huge collection – they claim to add 30 every week. But, the ones that are there are really well done and I would suggest well worth the time to bookmark and search when you don’t have an image of your own to use.