Using images for coursework, exams, theses
If a webpage or site is created as part of an assessed piece of coursework, dissertation or thesis, and will not be made available to anyone except the assessor(s), you can include images and other material without infringing copyright. But if the page will be made available to a wider audience, even to students in the same class (unless their comments contribute to the assessment mark), you should get permission in the usual way.
Under the Copyright, Designs and Patents Act (section 32) you may copy anything for the purposes of examination / inclusion in a thesis, although any copyright material should be removed if the exam paper / thesis is subsequently published.
All non-original material must be correctly acknowledged with a proper reference to its source. This is good academic practice and avoids any suspicion of plagiarism.