Focusing primarily on current problem areas in mathematics instruction, this third yearbook of the Finnish Association of Mathematics and Science Education Research contains five articles addressing four themes in mathematics education. The first theme is concerned with proportional reasoning in mathematics teaching and describes school test developments in the area. The next two articles deal with geometry teaching; the first outlines the aspects of instruction while the second discusses the role of computers in teaching. The third theme examines problem solving and the fourth describes learning difficulties of 13-year-old students in basic arithmetic operations. Biographic notes of the contributing authors are also included. (ML)