Poster Angles

Multiplication tables

Poster and mug to learn the multiplication tables.
Geometry Poster

Geometry Posters

Poster with 96 images of geometry.

The Chinese Remainder Clock

A mathematical clock based on the Chinese Remainder Theorem.

Math around the Clock

Various original mathematical clocks.
Sliding mask

Visualizing recurrence sequences

A sliding mask to understand recurrence sequences.
  • Unmasking recurrence sequences, Pi in the Sky (Issue 21, 2019).
Sliding mask

Multisets in Arithmetic

About the multiset of prime factors.
  • Multisets in Arithmetic, to appear in Plus Magazine.
  • Discover multisets, pdf, basis for the article Multiverzamelingen, Uitwiskeling (vol. 35, no. 4).

Mathematical Induction

Illustrating the Principle of Mathematical Induction.
  • with Milko Todorovic, the article Visualizations for the Principle of Mathematical Induction (here the Slides) about the variants of the Principle of Mathematical Induction and how to illustrate them.
Zeit Quiz

Mathematical Quizzes

One Quiz about plane geometry.
Master Mind Rad

The Mastermind Wheel

A didactical tool for understanding Knuth's algorithm for winning Mastermind in at most five moves.


A didactical card game for learning the Congruence and Similarity Theorems for triangles.
  • Sim!Cong!, The instructions and the set of printable cards (free for personal use, or use in class for instructors).
  • Leaflet, Guidelines for commercial use (University of Luxembourg).

5-Con triangles

Triangles that are almost congruent.
Arithmetic billiard

Arithmetic billiards

A geometric construction for the gcd and the lcm.
Mathematik zum Anfassen

Mathematik zum Anfassen

Documentation about the mobile exhibition of the mathematikum.
  • With the students of the Master of Secondary Education, the detailed description of the exhibition Mathematik zum Anfassen of the mathematikum. With Bruno Teheux, slides explaining some of the exhibits.
Plimpton 322

History of mathematics

The Babylonian tablet Plimpton 322.
  • with Deborah Stranen, the article Understanding the Babylonian tablet 'Plimpton 322' with the decimal system (here the Slides).
"Understanding the Babylonian table 'Plimpton 322' with the decimal system makes an interesting contribution to the history of mathematics." (Reviewer)


Sines and cosines expressed by radicals.
Mathematical riddles

Mathematical riddles

The Hardest Logic Puzzle Ever. Mathematical riddles for everyone.
  • with Jerry Hilgert, Riddelicious, mathematical riddles set in the Luxembourgish context, in English, German, French.
Mockingjay 15-puzzle

Further mathematical articles

Mockingjay Mathematics (movie-inspired problems). The Art Gallery Problem.
  • The article The Art Gallery Problem.
The 15-puzzle. The 'Four points, two distances' problem.
  • The article Four points, two distances.
The 7 bridges problem.
  • The article The seven bridges of Königsberg.

Further mathematical exhibits

Drehoskop (to explore solids).
  • With Edith Wittman, Drehoskop, a tool to detect rotational symmetries for polyhedra (these can rotate on various axes).
A mathematical exhibit around Pythagoras' Theorem.
  • PytEuk, an exhibit that shows Pythagoras' Theorem and some related result by means of puzzles.
Placing the numbers 1,3, and 5.
  • The 135 Exhibit, with two formulas related to the number 135, pdf.
GoFlex (composable flexible stripes).
  • GoFlex, reconfigurable flexible stripes to create Möbius bands and other geometrical objects.