The 1st of June, usually a joyful day dedicated to the protection of children by UNESCO, was a sad day this year. On this day in 2021 Professor Pentti Hakkarainen passed away. Pentti was a prominent psychologist and methodologist of activity theory and cultural-historical approach. Starting with the translation of Leontiev's book “Activity, Consciousness, and Personality” (1977) into Finnish, he continued to penetrate into the depths of activity and cultural-historical theory during his scientific career.
Keywords:
Pentti Hakkarainen; activity theory; cultural-historical approach
