Wikimedia Commons is a media file repository containing pictures, sounds and videos that you can use on your website. Wikipedia and its sister projects, including Wikimedia Commons, operate under a Creative Commons licence. The rules for using and distributing their works are available on their websites.
It is not as simple to use as something like Photopin, with its ability to select your size and have the attribution information to hand, but there is an increasingly vast selection of media for you to use. A benefit of using Wikimedia Commons is that there are more than photographs available. Aside from the audio-visual content there are a variety of diagrams and illustrations.
There are a number of options for using a picture/ file including ‘download’ and ‘use on the web’. By clicking on these options you will see how you can select the size you want and the attribution information you need. The ‘use on the web’ option contains the HTML code for you to paste into the ‘text’ element of your post. This will automatically link back to Wikimedia Commons.
It really is worth having a look at the images and files that are available here as you may find things to use across the curriculum, not just within blogging.