2023/24: Let's build Sonobe polyhedra

Modular origami involves building wonderful large objects from simple units. The Sonobe unit impresses with its simplicity and flexibility and is well suited to building star-like polyhedra. It consists of a parallelogram with angles of 45 and 135 degrees, which is folded on three lines in total like a wave. In the middle part there are two pockets into which the tips of the other units can be placed. Depending on the (diagonal) folding of the square middle part, a wide variety of geometric bodies can then be built.

This year we want to build many different colored polyhedra from Sonobe units together. For this we use square paper with a side length of 9cm. We invite the community to build Sonobe units from a variety of papers in advance, possibly decorate them, and then put them together into many colorful polyhedra during the HEGL Christmas activity. See  the poster with a manual for building the Sonobe units.

2022/23: Let it snow! - Fractal Koch Snowflake

Replacing the middle third of a given length by the two segments of the same length that form an equilateral triangle with the replaced one, is one step of iteration to construct a Koch curve. The Koch curve is the limit of this iteration process. Three such curves together form a Koch snowflake, a nice fractal with a fractal dimension of about 1.262, which has infinite circumference but finite area.

This time we asked the community to build a fractal snowflake together. We distributed little Koch snowflakes and asked everyone to write or draw something related to math and/or winter on it. Thanks to many enthusiastic participants, we created a big snowflake out of 216 small ones and displayed it in the foyer of the Mathematikon. For more information and pictures, see the poster (in English and German), the explanations in English or German and the HEGL gallery.

2021/22: Sierpinski Christmas Tree

The Sierpinksi triangle is a well-known fractal in two dimensions. Its pendant in three dimensions is the Sierpinski tetrahedron, where four small tetrahedra together form a bigger one. The fractal dimension of the Sierpinski tetrahedron is 2, which is the dimension of a plane, although the tetrahedron in a 3-dimensional object. Seen from the right perspective, the surfaces of the small tetrahedra form a plane without gaps and without overlappings.

We invited everyone to create one or more small tetrahedra and built a nice Sierpinski Christmas Tree out of them. For more information and pictures, see the poster and the HEGL gallery.

Am Tag der Mathematik laden wir  Schulen aus der Umgebung ein, mit kleineren Teams aus Unter-, Mittel- und Oberstufe an einem Tag an dem sich alles rund um die Mathematik dreht teilzunehmen.

Der Vormittag besteht aus spannenden Vorträgen, in den letzten Jahren zum Beispiel:

• „Was macht der Nikolaus im Sommer? Euler-Graphen im Hausbau“
• „Codierungstheorie und Lineare Codes“
• „Konkrete Kunst und Mathematik - Visualisieren und Interpretieren“
• „Von der Geradengleichung zum ganzzahlig-linearen Programm“

Und einem Teamwettbewerb.

Am Nachmittag erhalten die Schüler, je nach Altersstufe, Einblicke ins Mathematik Studium, oder können sich ganz praktisch an Stationen probieren.