Logic

Mathematics

Shape and Space

Shapes

Solids

847 Compass needles

Magnetic Domains. There are 847 compass needles attached to a disc. Because they are so close together, they influence each other. With a magnet, the compass…

A riddle for intelligent and patient people

Puzzles for the sharp-minded and patient. Trickier than it seems: these eleven puzzles with strings, boards, and rings are challenging. One of them cannot be…

A Table with loose Legs

Three, two, one – stable. How many supports do we need to stabilize a tabletop? Without screws, without glue, of course. Sharp-minded (and experimental)…

All Triangels are the same

Central projection: Using various triangular shapes to cast congruent shadows onto a patterned wall with equilateral triangles.

Angled Mirrors

Many polygons. Two mirrors positioned around an axis at various angles: a simple way to create shapes with many sides (polygons). At certain angles,…

Ball in a Bowl

Shorter path = faster to the goal? A question that occupied the best mathematicians three hundred years ago. This competition compares two parallel tracks,…

Ball sorting machine

Playful tidying up. Yellow. Red. Blue. This machine sorts the small, medium, and large balls among Pierre Andrès' “Machines Singulières” in a playful manner.…

Beam Bridge

The simplest form, but not the most stable. This bridge demonstrates the forces acting on a straight beam when it is loaded and supported only at its two…

Bouncing (Steel) Ball

Ping-ping, not ping-pong. When a ping-pong ball drops onto the table, its sound is unmistakable. A tapping noise that grows quicker and quicker. This happens…

Break the code

Qxpoa gvp pbuu: Cryptography. An encrypted text appears on the monitor. The challenge is to decrypt it with as few errors as possible. But there are over four…

Bridge the Gap

Building bridges is not so easy - especially when you are not allowed to use nails, screws or glue! Here you only have nine identical wooden blocks at your…

Catenary Arch

Building solid – like the Romans. An arch as a delicate structure: reconstructing what the Romans perfected. Understanding what gives their elegant arches…

Chance Happenings

Capturing randomness – with dice. Four faces of these dice are white. The other two faces show a red circle. After each roll, the dice with the red circle…

Changeable Weather

How do you determine the average value of numerous individual measurements? Here, the average monthly rainfall can be determined experimentally.

Christmas Balls

Round shapes, angular gaps. The spheres are indeed round, despite the triangular gaps between them. Can this really be? If a sphere is missing in the…

Conic Sections with Laser

Ellipse, parabola, hyperbolic branch, or hyperbolic arm: Cross-sections of a plane through a geometric body. In this case, a cone. A laser beam circling the…

Convection cells

«Convection Cells» Warm air rises, as does warm liquid. This forces air and moisture to descend in other areas. The structures that form resemble cauliflower…

Conway Cube

Test your spatial imagination. Assemble nine pieces to form a cube. Three 1x1x1 cubes and six 2x2x1 cuboids. It seems simple, what the renowned British…

Diced Snake

At some point, it’s probably going to work... All sixty dice lined up: what number shows the head of the snake? Now move forward by that number. Roll the…

Digital Sundial

"Digital" sundial. It casts no shadow. Instead, it displays the time using illuminated numbers—without any electronics. A combination of aesthetics and…

Disappearing Ghost

The ghost disappears. Where did it go? The ghost reappears. Where did it come from? A puzzle made of three parts: one base element, two pieces to swap. How…

Distorted Room (Ames Room)

Little one grows tall. An absolutely ordinary room, at least when viewed through the peephole. But wait, the little brother grows taller than the big sister…

Drawing on the Move

Elegant circles, spirals, and ellipses. Above a disc with variable rotational speed lies a ruler. If the pen is held still along the ruler, circles are drawn.…

Efron’s Dice

Loaded dice. The numbers on the faces of these four dice are nothing like what we’re used to. And they really get your brain working. The first player picks…