Option 1: Some Chromebook keyboards feature a dedicated screenshot button that only need a single press to get started - you’ll always find it on the top row and generally speaking, it will be between your overview buttons and the brightness adjustments.
Option 2: Simply press the CTRL+SHIFT+OVERVIEW key combination and the screenshot tool will appear.
Option 3: Simply click on your clock to open the system tray and then click the "Screen capture" shortcut you see on the pop-up menu.
Once you have opened the tool you can choose between making a static image or a video sequence. You can select from your entire screen, a resizable portion of the screen, or an individual app window and choose a download folder for your finished media.
Static images
For images simply set your parameters in the settings menu and click the button in the centre of the capture area.
Video sequences
For videos use the settings menu to enable/disable the microphone, choose the camera you want to use to add your face in the corner of the screen, enable clicks and keypresses to be shown on your recordings. Additionally the floating selfie cam can be moved to any of the four corners of your video recording and can be resized to the standard or smaller option.
Once you start the recording, you can stop it by clicking the stop button that is conveniently located in your system tray on the lower-right-hand side.
Click here to see an Android Police article that details the above 'Native' facilities.
Click here to see an a TechRepublic article that covers the same features but also recommends other 3rd party tools for the job.
Click here to see a Chrome Unboxed article from Feb 2022 called "How to take a scrolling screenshot on your Chromebook or in the Chrome browser"