What can I use?

An important point to note is that just because something is published on the internet, it does not mean it can be downloaded, copied or used.

If you find something you think could be a useful part of your training, you need to check if you are allowed to reuse it and if there are any conditions to meet. This applies to text, photos, diagrams, videos and any other type of online material, and it applies whether you’re looking to reuse it in its original form or adapt it for your own purpose. It may be that the only requirement is to include written acknowledgement of your source but it is important that you check for any other conditions.

A good way of overcoming these problems is to look for Open Educational Resources.