Seven pieces that make a square
A tangram is a dissection puzzle: a square cut into seven flat pieces called tans - two large triangles, one medium triangle, two small triangles, a square, and a parallelogram. The puzzle is to rearrange those seven pieces into a given silhouette: an animal, a boat, a letter, or a geometric figure.
Three rules define every tangram figure: all seven tans must be used, they may not overlap, and they must lie flat. Rotation is always allowed, and the parallelogram - the only asymmetric piece - may be flipped. Because the seven pieces always add up to the same area, every legitimate silhouette has exactly the area of the original square, which is part of why solutions feel so satisfyingly exact.
From Qing-dynasty China to a worldwide craze
The tangram emerged in China near the end of the 18th century, where it was known as qiqiaoban - the 'seven boards of skill'. Trade ships carried sets to Europe and America in the 1810s, and the puzzle became a full-blown craze: newspapers printed silhouette challenges, carved ivory sets crossed the Atlantic, and books of hundreds of figures appeared within a few years.
The name 'tangram' itself first appeared in print in the 1840s, and the puzzle has never really left. Mathematicians later took it seriously too: a 1942 proof catalogued exactly thirteen convex shapes the seven tans can form - you can try several of them in our classic figures collection.
Why tangram endures
Tangram survives because it hides real geometry inside a toy. A silhouette gives you the outline but not the internal boundaries, so solving one is an exercise in decomposition: which corners must be triangle tips, where the parallelogram's slant can and cannot go, which large region secretly needs the two big triangles side by side.
It is also gentle to learn and hard to exhaust - children solve their first figures in minutes, while the hardest silhouettes stall experienced solvers. Playing online adds what paper never could: instant snapping, a daily shared puzzle, difficulty tiers, and an endless supply of new figures.