Four Cubes Outlines Puzzle:
In the illustration four flat cube-like shapes are shown. Their patterns
are drawn with bold black lines. Which of the outlines can you draw
without taking your pencil off the paper or going along the same line
twice? Which of them can't be drawn in this way?
(Solution on Page XX

Solution to Puzzle on Page YY: (PLEASE PUT THIS ON A DIFFERENT PAGE)
Shapes A and D can be drawn without taking your pencil off the paper or
going along the same line twice. Shapes B and C can't be drawn in this
way.