A "wandering mind" refers to a state where our thoughts constantly shift and jump from one thing to another, making it challenging to focus on the present moment or a specific task. Full definition
This is where I want to wander my mind back and under, past the smell, past the thumpbump of the boots and the suitcases, toward some semblance of a good - bye. (bookbrowse.com)
Studying (often) = boredom / wandering mind = supposed need for a snack = spoon + nut butter (+ / - celery). (californiaendlesssummer.com)
WANDERING MIND In an anthology of wide - ranging essays, neurologist and author Oliver Sacks celebrates the beauty — and mysteries — of the world and the people, animals and plants that inhabit it. (sciencenews.org)