Writing an analysis about crypto in school

So today I was told by my teacher that I should write an analysis about something interesting and I chose to write about cryptocurrency, don't know why I chose it but I did. I have only written on the analysis for about 2 hours but I am finished mostly because I know crypto quite well imo and it was only a search for good pictures for my presentation. The only thing I find hard is explaining what crypto is on a basic level with using less than 30 seconds as that is the time limit for that part. Have any of you guys reading ever explained to someone who doesn't​ know anything about crypto what it is in such a small time, if you have please tell me how you did it.

Thanks for reading!