Future jobs will require students to handle interdisciplinary knowledge that goes beyond computing techniques when it comes to mathematics education. The traditional approach to education insufficiently develops the needed mathematical skills and mathematical literacy and there is a need to devise new methods of teaching and learning. We introduce game-based learning in mathematics education through carefully designed activities aiming at interdisciplinarity and increasing students’ motivation, mathematical and digital literacy, physical activity, level of knowledge, etc. We propose the treasure hunt cantered around cryptography as an example activity that satisfies the described criteria. Parts of the clues leading to the treasure are hidden using different ciphers, following the historical development of cryptography. The treasure hunt is time-limited to one hour and, to successfully complete the search, students need to learn, adapt, and apply different methods of encryption and decryption. To complete the hunt in time, students must work as a team and effectively divide the tasks among themselves. Students have at their disposal all instructions and manuals in written form, and they are compelled to read with comprehension. We conducted the activity with several groups of high school students with no previous knowledge and skills in the field of cryptography. Students were asked to take a pre-test and post-test survey about their experience and familiarity with cryptography concepts. Most teams completed the search and achieved all learning outcomes. In the paper, we will describe the activity in detail, analyse the test results and give additional examples of game-based activities in mathematics education.

A construction of designs acted on by simple primitive groups is used to find some 1-designs and associated self-orthogonal, decomposable and irreducible codes that admit the simple group ${\rm He}$ of Held as an automorphism group. The properties of the codes are given and links with modular representation theory are established. Further, we introduce a method of constructing self-orthogonal binary codes from orbit matrices of weakly self-orthogonal designs. Furthermore, from the support designs of the obtained self-orthogonal codes we construct strongly regular graphs with parameters (21, 10, 3, 6), (28, 12, 6, 4), (49, 12, 5, 2), (49, 18, 7, 6), (56, 10, 0, 2), (63, 30, 13, 15), (105, 32, 4, 12), (112, 30, 2, 10) and (120, 42, 8, 18).

We construct self-orthogonal codes from the row span over F2 or F3 of the adjacency matrices of some strongly regular graphs defined by the rank-3 action of the simple unitary group U4(3) on the conjugacy classes of some of its maximal subgroups. We establish some properties of these codes and the nature of some classes of codewords