14 Apr

Call for Puzzles

Hey, I have recently become problem editor for the undergraduate Math Horizons magazine of the Mathematical Association of America. So I’d love if you have problems/mathematical puzzles to submit to the column. The official submission blurb follows, and of course you will be credited in the Magazine. The Playground features problems for students at the… [Read more]

11 Apr

Side of Spherical Square

This post contains the details of the claim made in “More Spherical Construction” that you can determine the side length of a spherical square from the ratio between the lengths of its diagonals. We’ll do this on a sphere of radius one; everything scales by a factor of the radius for a general sphere. The… [Read more]

10 Apr

Gengzhi Goblets

One might think that having produced prototypes of the Gengzhi Goblets, our work is just about done to produce sufficient quantity (roughly 300 of each) to serve as G4G13 giveaways. The question comes down to materials and expense. If the Gengzhi Goblets are actually to be used as measuring cups, then they need to be… [Read more]

10 Apr

Archimedean Variations

So I had zeroed in on the proof of the Archimedean volume relationship as the source of my giveaway for G4G13. But how to create an interesting variation? The first thing to notice is that the function of h that appears in the proof in the cross-sectional area of of the cone, namely h², could… [Read more]

09 Apr

Mathematical Free Association

So it became time to decide on Studio Infinity’s giveaway at the 13th Gathering for Gardner (G4G13). By tradition, at least, it’s considered a plus for giveaways to connect with the number of the conference — 13 in this case. So this mathematical free association starts with the number 13. What thoughts does 13 evoke?… [Read more]

05 Apr


In addition to the main, planned build at the Golden Gate STEM Fair, and thanks to donations of materials from Primed Minds, there was also a do-it-yourself/take-home table at the STEM Fair. Participants produced such towers as this one: However, this column isn’t mainly about the inquisitive fun that participants at the take-home table had,… [Read more]

05 Apr

GGSF: Prep

A brief post about the importance of prepping and prototyping for a build, and a couple of things that came up in the prep for the Golden Gate STEM Fair event. First, there’s just the sheer volume of supplies for such an event. Here are lots of beads getting outfitted with twist ties, for example.… [Read more]

05 Apr

GGSF: Calculations

This post just takes care of some of the calculations used in planning the Golden Gate STEM Fair event. First, the plan was to make the structure shown at the right: a regular tetrahedron on top of a regular octahedron. Moreover, the resulting construction was intended to be five meters tall. Hence, the question arises:… [Read more]