Identifying is all about recognising the need for information.
When you begin an assignment it's crucial you make sure you understand the assignment brief. If you have any doubts ask the person who set the assignment for clarification. Start by explaining your interpretation of the assignment brief to them; with any luck they'll say "that's right, your understanding of the assignment is spot on", but if they don't, they should be able to use what you've told them to get you back on track pretty quickly.
Once you fully understand your assignment brief you can identify what you do and don't already know and, therefore, what you need to find out.
Just as important as understanding your assignment brief is understanding the specialist terminology used in libraries and assignment research: click on the pdf link below to familiarise yourself with some of the most commonly used words and phrases.
One of the terms listed in the glossary is 'peer review'. For a more in-depth explanation of peer review and why it's important watch this video by North Carolina State University Libraries called Peer Review in Three Minutes.