Polyominoes have been used in popular puzzles since at least 1907, and the enumeration of pentominoes is dated to antiquity. Many results with the pieces of 1 to 6 squares were first published in Fairy Chess Review between the years 1937 to 1957, under the name of "dissection problems." The name polyomino was invented by Solomon W. Golomb in 1953 and it was popularized by Martin Gardner*.
A polyomino** is a shape that consists of square units pasted together. It is an extension of the word domino, two squares placed side by side. But the word poly means many, hence we may have many squares arranged to form a particular shape. Can this piece be used, over and over again, to tile a rectangle? If so, the “order” of a polyomino is the smallest number of pieces that will tile a rectangle. It is notoriously difficult to determine the order of even modest polyominoes.
We used game figures composed of different numbers of squares.
* Martin Gardner (October 21, 1914 – May 22, 2010) was an American popular mathematics and popular science writer, with interests also encompassing micromagic, scientific skepticism, philosophy, religion, and literature—especially the writings of Lewis Carroll and G.K. Chesterton.
** Polyominoes are classified according to how many cells they have (1 - monomino, 2 - domino, 3 - tromino, 4 - tetromino, 5 - pentomino, 6 - hexomino and etc.)