Tiling with Pentominos
Polyominoes are plane figures made by attaching nonoverlapping squares to each other in such a way that any two attached squares have one side in common. Pentominoes are polyominoes that use five squares; there are 12 free pentominoes (i.e. they can be turned or flipped over). Find some of the 2339 tilings of a 6×10 rectangle by pentominoes constructed from unit squares . To rotate a piece, click its locator and drag. To translate a piece, click near the locator and drag. To reflect, click a vertex.
 W. J. Hansen. "Equivalence Classes Among Pentomino Tilings of the 6x10 Rectangle." (Jan 27, 2014) www.cs.cmu.edu/~wjh/papers/hexclass.html.