# Think You Know The Solution To This Classic Riddle? Think Again.

Today's puzzle will be posed in two halves. The first half is a classic riddle – in fact, I suspect many of you will have heard it before. The second half, however, is an extension of the riddle that reveals its most common solution be be insufficient.

# The Best Kind of Math Is Edible, Chocolate Math

Chocolatier Rafael Mutter's *Chocolate Mill *looks like a solid, cylindrical block of chocolate. In reality, it's ten-layers thick. As a a crank-turned blade shaves wafers of chocolate from the top, the underlying layers, each one flavored with a unique pattern of chocolate shapes, is revealed.

# Celebrating Jean-Félix Picard's Birthday With Geodetic Trivia

If you find having a favourite map projection a delightfully geeky quirk, you're going to want to raise a toast in honour of Jean-Félix Picard. Geodetics and cartography owe a debt of gratitude to the 17th century scientist who made the first accurate measurement of the Earth's size.

# A Massive Crop Circle Appeared Overnight In Italy

An intricate crop circle, pictured here, materialized last night in Poirino, Italy. This aerial view gives you a good sense of scale. See those cars in the upper left hand corner? Yeah. This thing's a biggie.

# Space-Pi!

Pi is for planets, and spacecraft, for orbital dynamics and craters. It's 3.14, and it's all about circles.

# Geometric sand sculptures put your bucket-and-trowel creations to shame

The cubist creations of sandcastle artist Calvin Seibert will blow you away.

# I can't stop watching this door open & close

Add this to the list of things we never knew existed but now desperately need: The Evolution Door, a "flip-panel" invention by Austrian designer Klemens Torggler.

# All I want for Christmas are these badass Euclidian sculptures

From London-based "paper engineer" (paper engineer!) Helen Friel comes this creative collection of colorful folding geometric designs. The name of the collection? "Here's looking at Euclid." GEOMETRY PUNS! We must have these.

# How To: Make geometric models out of straws and coffee stirrers

Over at Make Magazine, Iann Gonsher shares this remarkably simple (not to mention totally free, if you count your latte as admission) method for building cool geometric models. "The baristas don’t tend to mind," he writes, "especially if you tip generously."

# What does a heart's sine function look like?

In high school, you probably learned that trigonometric functions – like sine, cosine and tangent –can be derived, geometrically, from a circle (hence why trig functions are also known as "circular" functions). But what happens if you use a square to derive these functions, instead? Or a triangle? Or a heart?

# Whimsical, animal-filled illustrations of mathematical concepts

Kasia Jackowska's *Drawing Mathematics* series takes an unusually adorable approach to illustrating mathematical concepts. The Pythagorean Theorem and Sierpinski triangles are conveyed through drawings of elephants, snakes, and deer.

# DeLand's Paradox is an illusion that can "disappear" a whole person

Let's say you are cornered by your worst enemy. They will kill you, but being an oddball enemy, they'll give you one request first. (And the request can't be "Don't kill me." They're on to that one.) I have a solution for you. Ask them to show you how DeLand's Paradox works. That will keep them busy for years while…

# The Ultimate List of Reasons We Know the Earth is Definitely Round

In case you had any lingering doubts, here is some masterful cosmological/geological/geometrical instruction on our planet and its spherical — but not *perfectly* spherical — tendencies, courtesy of the ever-capable Henry Reich (better known as the creator, animator and narrator of MinutePhysics). Some great, if not…