While a demonstration is not a compulsory component of your MSc summer project, there are many circumstances in which providing your supervisor and your second marker with a demo will enable them to assess your achievements more accurately.
If you do decide to give them a demo, then your examiners will need to be convinced that:
You should also try to educate the examiners by clearly presenting:
As a guide to pitching the level of your explanations, assume that your examiners are ignorant of the particular problem you are investigating, but have a general background in the subject area. Often the second examiner is from outside your project area. So, be sure to introduce your project properly, don't just dive into the middle. What were the aims of the project, how did you go about achieving them, what results did you obtain, what difficulties did you have?
In a typical demo, you might:
Not all projects will follow this outline; modify it to suit your own particular project.
A demo should take about 20 minutes. You will probably find that this is quite a short time, but it is good practice to do it in this time because this is typically the time you will have to demo a system in other scenarios; e.g., at conferences. Given that 20 minutes is not long, you should:
Two related mistakes that even good students make are: trying to tell the audience EVERYTHING about their project, instead of an overview; and spending too much time giving a lecture about the project instead of using the time to show things working (which is the main reason for the demo).