If you need to walk away from your Chromebook and keep a stranger from using it, then lock it with Search/Launcher + L. Press Shift + Alt + M to open the Files app. If you want to preview a file ...
There are multiple ways to unblock websites on school Chromebook devices. You can try using a VPN, connecting to a proxy server, changing the site permissions, and accessing websites using the IP ...
The simplest way to record audio on Chromebook devices is to use the official Recorder app. It's pre-installed on most modern Chromebooks, so you simply have to find it in your apps and launch it.