One of the ways to take screenshots on hp Chromebook is by using Quick Settings panel, which is one of the ways to access the screenshot tools. This comes in handy if by chance you forget the combination of hotkeys, or it might be hard for you to press three keys at the same moment. To get to Quick Settings, search for the shortcut button on the Chrome's Shelf which is located on the clock.
Through the settings, you'll be able to see the menu pop up from which you can look for the Screen Capture option which will launch toolbar. From here, you will be able to take the screenshot you require, it can be partial screen or full screenshot.