Mr Honner

05/21/2015 — Happy Derangement Day!

Today we celebrate a Derangement Day! Usually I call a day like today a permutation day because the digits of the day and month can be rearranged to form the year, but there’s something extra special about today’s date:

The numbers of the month and day are a derangement of the year: that is, they are a permutation of the digits of the year in which no digit remains in its original place!

Derangements pop up in some interesting places, and are connected to many rich mathematical ideas. The question “How many derangements of n objects are there?” is a fun and classic application of the principle of inclusion-exclusion. Derangements also figure in to some calculations of e and rook polynomials.

So enjoy Derangement Day! Today, it’s ok to be totally out of order.

By MrHonner, 11 yearsMay 21, 2015 ago

3D Printing Appreciation Geometry

3D-Printed Chmutov Surface

My most successful 3D print so far: a Chmutov surface!

Chmutov surfaces are algebraic surfaces that have interesting properties involving their singular points. This surface has equation

$2[x^2(3-4x^2)^2 + y^2(3-4y^2)^2 + z^2(3-4z^2)^2]=3$

And in addition to being quite beautiful, this Chmutov surface is already coming in handy!

By MrHonner, 11 yearsMay 14, 2015 ago

Appreciation Numbers

05/12/2015 — Happy Permutation Day!

Today we celebrate the third Permutation Day of the year! I call days like today permutation days because the digits of the day and the month can be rearranged to form the year.

Celebrate Permutation Day by mixing things up! Try doing things in a different order today. Just remember, for some operations, order definitely matters!

By MrHonner, 11 yearsMay 12, 2015 ago

Numbers Resources

Fun with SumBlox

We have been having fun with our SumBlox, which recently arrived. The number blocks are cleverly designed so that the height of each is proportional to its value.

Here we have the ten block

and here we have multiple mathematical ways to achieve the same height as the ten block: five + five, three + seven, and nine + one.

So far, playing with SumBlox seems like a fun way to build number sense and explore basic properties of addition like equivalence and commutativity. But there does seem to be one problem: I think they got the height of this block wrong!

By MrHonner, 11 yearsMay 10, 2015 ago

Challenge Resources Teaching

Rosenthal Prize Application Workshop

I recently participated in a workshop hosted by the Museum of Mathematics about the Rosenthal Prize for Innovation in Math Teaching. The Rosenthal Prize invites classroom teachers to submit outstanding, fun, creative, and engaging math lessons: the author of the best lesson receives $25,000, and other noteworthy submissions are honored as well.

The purpose of the workshop was to help prospective applicants understand the submission, revision, and judging process for the prize. The workshop panel included the directors of the museum, past judges, and three former winners of the Rosenthal Prize (including myself).

The video is embedded below, or you can watch on YouTube here.

Please spread the word about the Rosenthal Prize: it’s rare to have such incentive to build and share creative, engaging mathematics lessons!

By MrHonner, 11 yearsMay 4, 2015 ago

05/21/2015 — Happy Derangement Day!

3D-Printed Chmutov Surface

05/12/2015 — Happy Permutation Day!

Fun with SumBlox

Rosenthal Prize Application Workshop

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