Christmas and Winter Holidays

In order of appearance, here’s Vi Hart things with Christmas, snow, and winter holiday theme.


The Gauss Christmath Special

How many presents are there in all? Framed by the song “The Twelve Days of Christmath” (a parody of the traditional, but with math things instead of birds and stuff), this Christmath special talks about triangular numbers, ways to add stuff, and a famous story about the mathematician Gauss.

Snow Day: You’re a Linkage

A quick comment on how snow angels can be thought of in terms of mathematics, particularly the study of linkages.


Snowflakes, Starflakes, and Swirlflakes

The symmetry of paper snowflakes, and how to make variations with different symmetries, including rotational symmetry.



Another variation on paper snowflakes, this time folding and cutting entire spheres by using deflated beach balls.

Oh What Fun

A variation on Jingle Bells, created Christmas Morning 2013



An interactive hyperbolic world aligned to a 12-tone version of the Twelve Days of Christmas, in collaboration with mathematician Henry Segerman. Originally for webVR, but it should work in your browser too:

Video of the work:

You can color and assemble your own 12-days dodecahedron with this dodecahedron craft:


And here’s just the song, The Twelve Tones of Christmas:

Joy To the World, 12-tone version:

What Child is This, 12-tone trio:

For more on 12-tone music, see Twelve Tones.


An art game made for VR, expanding “What Child is This” (as heard above) into a soundscape and gamescape. You can play it in a normal browser:

Video documentation:

Background soundscape:

More about this work:



A VR experiment in collision design and movement design, where you leave a path through a snowy landscape as you sled around collecting presents. It was programmed live over a twitch stream.

The game no longer works quite right as it was written for an old version of webVR using the spatially-tracked Vive devkit, and relies on spatial tracking for steering your sled, but the regular browser version can still be played with, kinda:

Some of the livestream has been archived, particularly the programming of the sled and the tree collision: and


A Snow Eagle endlessly melts and reforms, to wistful snowmelty music.


Christmas is cancelled



Another variation on the paper snowflake, this time using hexaflexagons (see the Hexaflexagons page for more on those).