I had been thinking about exercises to help players <1400 gain confidence. For instance, they should feel confident they can always win with queen and king vs king, or rook and king vs king, even against Magnus Carlsen. They should also feel confident they can win with a bishop and 8 pawns vs 8 pawns.
So I lazily took all the pieces off the back ranks and removed black's king pawn, to give an exercise with king and 8 pawns vs king and 7 pawns. I figured winning a pawn up in a pawn endgame is a useful skill to know, and it should not be too hard.
[FEN "4k3/pppp1ppp/8/8/8/8/PPPPPPPP/4K3 w - - 0 0"]
However, initial desultory poking around showed Black may be able to sit tight and form a barricade. This could be instructive for a beginning player, but it also might be too intimidating.
While this probably won't happen in actual play (exchanged pieces mean there is probably at least one line open), this is a non-trivial case worth looking at, as Black could quite possibly establish a blockade down two pawns (you can ignore the two backwards pawns--I saw this pawn structure in a recent video of Ben Feingold's, about his 2019 Foxwoods tourney.)
[FEN "8/4k3/1p4p1/p1pPPp1p/P1P2P1P/8/4K3/8 w - - 0 1"]
What is a good strategy for White to minimize the possibility of blockades? Also, what is Black's best strategy to push pawns and maximize the possibility of blockades?