You are always allowed to use scratch paper, a device with a webcam, and any other tools that are explicitly asked for on a unit test (such as a calculator). The Khan Academy tests have a built-in drawing tool that you can use to show your work on the screen if you would like. For example, if a calculator, graphing calculator, or a z table are recommended on the unit test, you may use one as long as you explain your work on the Khan Academy certification test questions.