Program Description | Application Process | Schedule | Pricing |  Policies


the high school track of Expansions, MoMath’s gifted math program to engage and challenge NYC’s brightest math students

Sundays, April 28 through June 2
3:30 pm to 5:00 pm ET

(in person)


Participation in Icosahedron is by admission only.

In the high school track of the Expansions gifted math program, Icosahedron students will join award-winning mathematician Chaim Goodman-Strauss for a hands-on, interactive mathematical exploration.  Learn about hyperbolic geometry and roll up your sleeves to make actual hyperbolic planes.  Explore complexity and the theory of computation by playing with unusual tiling problems.  Plus, by making tape-and-scissor surfaces, learn to apply topology to a cutting-edge theory of symmetry.  And be sure to dress appropriately for the weather when you come to class — at times, we’ll take all this outside, making things large!  Expansions is MoMath’s gifted after-school program designed to engage and challenge New York City’s brightest math students.  The program offers workshops designed and delivered by MoMath’s educational team to illuminate the wonders of mathematics, challenge and inspire students, and broaden their mathematical horizons!

Mathematician Chaim Goodman-Strauss is MoMath’s Outreach Educator and co-author of the recent groundbreaking papers on the Hat and Spectre tiles, the first-ever shapes in mathematics to tile the plane but only in a non-repeating way.  Chaim is also the winner of the 2021 Rosenthal Prize for Innovation and Inspiration in Math Teaching and a co-author with John H. Conway and Heidi Burgiel of The Symmetries of Things, a comprehensive book surveying the mathematical theory of patterns.

Application process

MoMath’s Expansions program offers a small class size approach, hands-on lessons, and a long-term, cohort model that builds dynamic groups of students who learn effectively together and return year after year.  Participation in Icosahedron (the high school track of Expansions) is by admissions only. 

Limited spots in Icosahedron are currently available.  Apply soon!

Your application will be reviewed and you will receive an email with instructions for next steps.


Icosahedron sessions will be held in person, from 3:30 pm to 5:00 pm, on the following Sundays: April 28, May 5, May 12, May 19, May 26, and June 2.


The registration fee for Icosahedron‘s spring 2024 semester, running from April 28 through June 2, is $595. Museum members at the Membership Squared level or above receive a 10% discount.  MoMath does not prorate fees for mid-term registrations, and refunds will not be given for absences or for any other reasons.  Museum admission is not included in the registration.

No refund will be provided for withdrawal from Icosahedron for any reason, including issues related to content level.

Need-based scholarships are available.  Scholarship applicants must meet the income guidelines of the federal Free and Reduced Lunch program and provide verification of household income.  Scholarship applicants should complete the regular application form online and send a separate email to with a request for scholarship application instructions.  Please allow at least two weeks for the scholarship committee’s review process.


MoMath will make every effort to run classes as scheduled, but occasionally unusual circumstances beyond MoMath’s control may require that a class be cancelled.  If such a cancellation occurs, MoMath may, at its sole discretion, offer make-up sessions.

Note that a particular level will run only if a minimum number of participants register before the start date of the full session.  In the rare event that a particular level is cancelled, registrants will be notified and provided with a full refund.

MoMath does not provide make-up classes for absences.  Each Expansions series accepts a limited enrollment in order to provide individualized attention to each student.  While many reasons may cause a student to miss a class, a registered student holds a reserved seat while others may be turned away due to limited capacity.  Additionally, the Museum provides staffing and other resources based on registration.  For these reasons, the Museum has a strict no-refund and no make-up policy.

All Expansions participants are expected to exhibit good behavior to ensure a positive experience for everyone.  At its sole discretion, MoMath may remove a student from the Expansions program for behavioral reasons.  If a student is removed for behavioral reasons, for either the day or the remainder of the program, no refund will be issued.