Spatial Visualization
Have you ever been challenged to imagine how a 2D shape, after being folded into 3D, will look like? This is the type of problem here. It might appear childish, but at a higher level it can be a fiendish problem to solve if your spatial thinking is not there (see the AMC 10 and AIME problems below for example)
Let Cubes be Cubes
Tips: the conversion from 3D-cube to 2D-joint squares (or vice versa) is my earliest experience with spatial visualization. I've heard people assigning numbers to different vertex and use the same number for vertex that merge in the end. To me, though, straightforward imagination has always been enough. Worst case scenario: draw on a piece of paper, tore it off, and fold it!
Coloring the Cube
Rolling, Reflecting, Folding,
1988 AJHSME Problem 24
1989 AJHSME Problem 11
1991 AJHSME Problem 16
1994 AJHSME Problem 4
2025 AMC 8 Problem 10 Problem 11 Problem 15