Whether they keep playing, or play for a while and then return, elementary endgames and basic tactics should serve them now and in the future.
My advanced students this week are grappling with a famous combination played by Paul Morphy at the First American Chess Congress. The whole game with analysis was posted yesterday at "Morphy's Immortal".
Black to move
For those students that find the combination, I will play Qd3 on White's third move from the diagram because Black's refutation is particularly challenging to find.
My beginning students this week, and some of my advanced students last week, are reviewing (or learning for the first time) "Six Pawn Endings" (see the Lesson of the week from mid-December at the link).