Unit 3 is the Non-Examined Assessment (new name for coursework) that's required to be submitted as part of the course.
It's a project, for all intents and purposes, and is down to you to arrive at and agree a title with your tutor.
Please see here for a guide from the exam board. Further advice can be found here.
Please see the following links for ideas of what's been done in the past, and the grades/levels of difficulty given.
A Mark scheme for this unit is found here.
An appropriate discussion board/forum is found here.
Below is 'decomposed' mark scheme that assists you with this project. It aims to steer you towards producing a good quality and high-scoring project. We strongly recommend that you take considerable time to read this piece of work before and while undertaking your project.