How do I Keep Track Of Performed Tasks

I would like to know how to do the following or at least the best way to get started.

I want a screen of tasks the user has to perform. The user clicks on a sprite/button and go to that particular layout to do the task. When the task has been completed, they are returned to the original screen of tasks with the task they just performed greyed out and no longer selectable.

Thank you in advance,

Use one global variable by task to keep track if it is completed or no and animate your sprite/buttons with the status of those variables.