Plagiarism applies to words and ideas. Simply changing someone else’s words is not enough. It is still their idea – acknowledge it. Plagiarism is defined as ‘using someone else’s words or ideas without properly acknowledging them or, put another way, presenting someone else’s words as your own’ (Pears & Shields, 2005, p.1).
Ignorance is no defence. Accidental plagiarism due to poor referencing is still an offence. If you do not know where something comes from do not use it. It is your responsibility to make sure you do not take material from a source without proper acknowledgement. When you are taking notes while reading make sure that you indicate where they come from e.g. list full details of the publication and record the page number(s) for the information you noted.
Plymouth University (2012) Essential information: Regulations: Plagiarism at: https://www1.plymouth.ac.uk/essentialinfo/regulations/Pages/Plagiarism.aspx (Accessed: 1 September 2012)
Pears, Richard & Shields, Graham (2005) Cite them right: referencing made easy. Newcastle: Northumbria University Press Trading Services.