A laboratory for hands-on mathematics
The Mathematikum in Gießen is the world's first interactive mathematics museum, opening its doors on November 19, 2002. It was founded by German mathematician Albrecht Beutelspacher, a professor at the University of Gießen who wanted to create a new way for people to experience mathematics. The concept grew from a university seminar on geometric models in 1994, which led to popular public exhibitions and a traveling show before finding a permanent home.
Today, the museum has over 170 interactive experiments across 1,200 square meters (about 13,000 square feet) of exhibition space. The guiding philosophy is "hands-on mathematics." Visitors learn through direct, sensory experience instead of abstract formulas and equations. The museum attracts more than 150,000 visitors annually, who come to engage with the puzzles, ball-racing tracks, and geometric constructions. In 2009, a dedicated "Mini-Mathematikum" was added for children aged four to eight, focusing on foundational concepts like numbers, shapes, and patterns.
From bubbles to bridges
The exhibits at the Mathematikum translate complex math ideas into physical activities. A popular station allows visitors to stand on a platform and pull a large, soap-dipped ring around themselves, forming a giant, cylindrical soap bubble. This shows the principle of minimal surfaces; the soap film naturally contracts to the smallest possible surface area for the volume of air it contains, a physical solution to a complex mathematical problem known as Plateau's problem. A single free-floating bubble is a sphere because that is the shape with the minimum surface area for a given volume.
Another well-known exhibit is the Leonardo Bridge. Visitors construct a self-supporting arched bridge using only identical wooden slats, without any nails, screws, or glue. The design, attributed to Leonardo da Vinci, relies on gravity and friction to lock the components into a stable structure strong enough to walk on. Other exhibits include square wheels that roll smoothly over a specially shaped surface, mirrors that create infinite reflections, and demonstrations of the Pythagorean theorem using scales. Visitors can also build catenary arches, the same curve formed by a hanging chain, which is important to architectural engineering.