PORTAANKORVA-KOIVISTO, Päivi; VIHOLAINEN, Antti. Collaboration, problem solving and other 21st century skills for teaching of mathematics at secondary level. LUMAT-B: International Journal on Math, Science and Technology Education, [S. l.], v. 7, n. 2, p. 86–102, 2022. Disponível em: https://journals.helsinki.fi/lumatb/article/view/1806. Acesso em: 5 dec. 2025.