cognitive – n. of, relating to, or involving mental activities (such as thinking, understanding, learning, and remembering)
session – n. a period of time that is used to perform activity
interleave – v. to organize in or as if in alternative or different levels
practice – n. an actual performance; a systemic exercise; the way of doing something
occasionally – adj. rarely; not very often
digital – adj. of or related to computer technology
deck – n. a set of playing cards
strategy – n. a careful method or plan
retention – n. the act of retaining; something retrained
discouraged – adj. feeling less determined, hopeful, or confident