In these days of working from home, you may need to explain how to do something visually on you computer. Windows 10 has a built in screen recorder in the Xbox Game Bar, and I’ve been using this to record short tutorials for this website, and for students accessing information for the first time online.
Unfortunately, the game bar only records the active window, not the whole desktop, and it can miss menus and things opening if they draw their own windows.
But for pointing out where things are, or what screens should look like, it’s indispensible, and I’ve already used it multiple times over the past few days to show students where to download things, or how to run software.
To get it enabled, open settings, and click on Gaming:
In there, make sure the ‘Enable Xbox Game Bar’ toggle is on, and that you have a shortcut (Win+G is the default):
Now when you want to record your screen, just press win+G, and the Xbox overlay will appear:
Click on the record button (the circle under ‘capture’ in the top left of my image), and windows will start recording whichever window was active when you invoked the game bar. It also records sound from your computer when doing this, so if you have a mic you can also enable recording from there.
Whilst recording, a small bar appears on your screen with the record time:
By default, the videos will be saved in Videos->Captures, but you can just click the banner that appears when you stop recording.
Hey look! Here I am testing the screen record function, so I can show you what it does! Or at least, some menus in my browser.
Dr Peter L. Falkingham 
Why not OBS ? You can use H265 there so that produce significant smaller files in most cases.
OBS is great, but it’s just one more thing to install, and has a learning curve to it beyond just clicking record. I’ve also found it can be quite resource hungry sometimes.
In such case you can use shadowrecorder if you have nvidia card. It use gpu for capturing to reduce lags and source usage.
Cracking idea! I’ve not tried shadowrecorder, thanks