### Raketti Puzzle

Versions of this puzzle avaioable fron these sources:

From CuriosityBox: **BUY NOW Raketti Physics Brain Teaser**

From Etsy: **BUY NOW Raketti Physics Puzzle **

Raketti Puzzle: a favorite physics brain teaser in my collection- the challenge is to remove the cone topped cylinder from the hole without touching the bottom container (no fair using sticky tape). It can be done in a matter of seconds! The solution to this puzzle (like others featured here) relies on some fun physics principles.

### Two Marble Puzzle

Great versions of the puzzle avaliable:

From Amazon:** BUY NOW: Two Marble Puzzle, **or get this** set of puzzles**

From Etsy:** BUY NOW: Two Marble Puzzles**

Similar 4 marble version of this puzzle available here:

From Etsy: **BUY NOW Four Marble Puzzle **

Two Marble Puzzle: physics brain teaser- move both marbles to their top locations on each side simultaneously. The solution to this puzzle relies on some fun basic physics principles- can you figure out which ones? Swipe to reveal solution. Found this well made version of this classic physics puzzle at a gift shop in San Francisco (note Golden Gate Bridge motif).

### Flippe Puzzle Ball

Get this puzzle ball here:

From Etsy:** BUY NOW: Flippe Puzzle Ball**

Flippe Ball Puzzle: this ball is a puzzle that explodes and flies apart when spun. The puzzle is made of three identical pieces and a ball bearing which mysteriously locks the pieces together only to release them after a period of spinning. The main challenge is to fully explain why this spontaneous disassembly occurs. Swipe to see a slow motion boomerang loop of it coming apart- and how conservation of momentum has the three equal mass pieces on equally spaced trajectories (120°) with the ball bearing remaining stationary at the center. A product of puzzle master George Bell.

### Four Marble Puzzle

Get this well crafted puzzle from Creative Crafthouse here:

From Amazon: **BUY NOW Crossroads Four Marble Puzzle **

From Etsy: **BUY NOW Four Marble Puzzle **

Four Marble Puzzle: physics brain teaser- move all four marbles to their corner locations simultaneously. Each slot slopes down towards the center such that the marbles tend to stay at the center- so, how would one get them to roll outward at the same time? The solution to this puzzle (like others featured here) relies on some fun basic physics principles. Answer below and swipe to reveal solution. A beautiful and well-made puzzle from Creative Crafthouse.

### TrueBalance

Get the full version (8 disks made of wood) or the mini (6 disks, blue or red plastic):

From Amazon: **BUY NOW TrueBalance Coordination Puzzle **

TrueBalance: coordination challenge puzzle- get the six disks, connected by bearing swivels, into a vertical stack by only tilting the handle. Harder than it looks to get each disk’s center of mass above the one below at the same time into the unstable equilibrium final state. The swivels constrain the system, limiting the degrees of freedom, and allowing strange and interesting motion. Kinetic art as a toy!

### Magnetic Soma Cube

Get this inexpensive SomaCube here:

From Amazon: **BUY NOW: Magnetic Soma Cube**

Magnetic Soma Cube: a new fun variant of the famous math toy invented by Danish scientist and artist Piet Hein, who claimed that this puzzle came to him as he was listening to a lecture on Quantum Mechanics by Werner Heisenberg (yes- that Heisenberg). The seven pieces of this puzzle are all the ways 3 or 4 cubes can be joined such that the piece has at least one inside corner. In this version small magnets are encased in cleverly designed cavities such that they will always flip over to attract a counterpart in another puzzle piece, allowing the puzzle to stick together- or hang from the side of the refrigerator. Amazingly there are 240 ways to make the cube from these 7 pieces- still not that easy!

### Matsuyama's Paradox

Get this and other amazing math puzzles here:

From Etsy: **BUY NOW: Missing Square Puzzle**

Matsuyama’s Paradox: dissect a large square in to four equal quadrilaterals, rotate and reassemble- to find a small square is missing! Where did the additional area come from? Fun math involved in the design of this puzzle, which illustrates how the concept of area can often challenge our intuitions. Swipe to compare the two assemblies. A precision crafted puzzle by Jeux Efcé game shop. Wikipedia has good details: Missing square puzzle.

### Stomachion Puzzle

Get this 3-color laser cut acrylic version here:

From Kadon Enterprises: **BUY NOW: Stomachion Puzzle**

Also a very nice multicolor acyrlic version here:

From Etsy: **BUY NOW: Stomachion Puzzle**

Learn about the 1998 discovery of the lost writings of Archimedes (and the technology used to recover them) in this TED talk.

Ancient Stomachion Puzzle: the oldest known puzzle, discovered in the writings of the great Greek physicist and mathematician Archimedes from some 2200 years ago. The puzzle is a dissection of a square into 14 polygons, where the areas of each piece are integer multiples of each other (a curious way to slice it up). In 2003 Bill Cutler showed that there are 536 district ways to configure these pieces to make the square (five are shown here), ignoring simple rotations and reflections. Swipe to see the most famous solution, attributed to Archimedes himself, that was found in an ancient manuscript discovered only in 1998- before this date historians knew the name of the puzzle, but no one knew what it looked like. Kate Jones, the maker of this particularly aesthetic version, found that when using only three colors for the polygons, there are only 6 solutions where no two pieces of the same color touch (four solutions shown here).

### Nova Plexus Interlocking Puzzle

Precision machined and available in brass or stainless steel:

From Art of Play: **BUY NOW: Nova Plexus Puzzle**

Nova Plexus Puzzle: 12 identical brass rods can create 4 interlocking triangles in a perfect symmetry- look carefully and you can see that each rod is in an identical configuration with the 5 others that connect with it. Precision machined notches on the ends of the rods allow them to interlock with elastic tension such that vector sum of the 5 forces on each rod is zero- creating this astonishing geometry as the equilibrium state. Unlock the ends of any two rods and the system instantly disassembles (swipe to view process in slow motion). Invented/designed by artist and computer scientist Geoff Wyvill in 1978, this puzzle has just recently been made available for sale with a limited production run.

### Soma Cube

The Soma Cube is available in a variety of materials and colors:

From Amazon: **BUY NOW: Soma Cube**

From Etsy: **BUY NOW: Soma Cube**

Soma Cube: Math toy invented by Danish scientist and artist Piet Hein, who claimed that this puzzle idea came to him as he was listening to a lecture on Quantum Mechanics by Werner Heisenberg (yes- that Heisenberg) in 1933. The seven pieces are all the ways 3 or 4 cubes can be joined, such that each piece has at least one inside corner. Amazingly there are 240 ways to make the larger cube from these 7 pieces- still not that easy!

### Impossible Braid

Get this nice example of mystery braid here:

From Art of Play:** BUY NOW: Impossible Braid Key Fob**

Here is a great video on how to make the mystery braid

See other **Impossible Objects** in my collection.

Mystery Braid: challenge- how can three strands be braided if both sets of ends are connected? (swipe for reveal) A new addition to my collection of “impossible objects”, this leather key fob is braided from a single piece of leather, constructed by making two parallel slits but not cutting the ends. The solution is well known to those in the field of leatherwork- due to a twist of topology it’s possible to make this braid if the number of left strand over right crossings equals the times the right strand crosses over the left. Four strands braided this way is not mathematically possible, but 3, 5, or any odd number can be done!

### 10 Hex Puzzle

This and other beautiful and well made puzzles are available on Etsy:

From Etsy: **BUY NOW 10 Hex Puzzle **

Two great resources about these polyhexs: polyform puzzler page and puzzleworld page

10 Hex Puzzle: this puzzle is comprised of pieces which are the set of all ways three and four hexagons can be joined with a common edge. There are 3 trihexs and 7 possible tetrahexs, and similar to pentominoes, these 10 polyhexs can assemble into a large hexagon. Amazingly there are exactly 12,290 solutions to this puzzle- but it’s still a challenge to find just one!

### Anamorphic Harry Potter Puzzle

No longer in production but available on eBay:

From eBay: **BUY NOW: Harry Potter On Reflection Puzzle**

Mirror Anamorphic Harry Potter: the conical mirror of the silver container reflects and reveals the distorted scenes in this 200 piece jigsaw puzzle of the famous wizard and school. The shape of the mirror allows for a mathematical operation, a type of affine transformation, to map the distorted image of the puzzle to the restored image reflected by the mirror. Real magic!

### Pentominoes

Get this set here:

From Etsy: **BUY NOW Hardwood Pentominoes **

Many versions available here:

From Amazon:** BUY NOW Pentominoes **

The book by mathematician Solomon Golomb that started the polyonomo recreational math craze:

From Amazon: **BUY NOW: Polyominoes **

Pentominoes: The 12 possible arrangements of five identical squares joined edge to edge. Since 5x12=60, the pentominoes can tile a 6 x 10 rectangle with no gaps (2339 ways to do this- yet even finding one solution is a challenge). I love this beautiful set from artist/woodworker Ron Moore where each pentomino is made from a different kind of hard wood.

### Tessellating Geckos

Laser cut geckos are available here:

From Etsy:** BUY NOW Tessellating Geckos **

Tessellating Geckos: MC Escher inspired lizard cutouts interlock precisely to tile a surface with no overlaps or gaps. Laser cut from maple, walnut, and cherry wood by maker/artist Craig Caesar and inspired by MC Escher’s “Study of Regular Division of a Plane with Reptiles” 1939. G4G week: Martin Gardner wrote about the art and math of Escher in 1961- which helped create the popularity that his work has experienced ever since.

### Ambiguous Superhero Object

### Cylindrical Lens Puzzle

A similar puzzle (but taking advantage of horizontal symmetry) available here:

From Educational Innovations: **BUY NOW Cylindrical Lens Puzzle **

Cylindrical Lens Puzzle: this cylinder of acrylic acts as lens that focuses light along a line rather than a point- and thus it can invert an image along its symmetry axis. Puzzle question: the word "GREEN" is flipped by this lens but the word "TOMATO" seems unaffected. Is the physics significantly different for red wavelengths as compare to green? Or is there another explanation/trick? Answer below.