The topic for this week is what in Pali is called "citta saṅkhāra." It's often translated as "mental formations," "mental dispositions," or "mental constructs." For this week, I have been using the expression "mental activities." It's the activities of the mind that are planning, creating, imagining, actively thinking about things. So a simple perception of something, like seeing a wall across the room, wouldn't necessarily be called an activity. It is an activity, but it's not one of the formations or constructions that we make.