Derivation of the law of radioactive decay is considered without prior knowledge of calculus or the exponential series. Calculus notation and exponential functions are used because ultimately they cannot be avoided, but they are introduced in a simple way and explained as needed. (Contains 10 figures, 1 box, and 1 table.)

This volume of the 27th International Group for the Psychology of Mathematics Education Conference presents the following research reports: (1) Text Talk, Body Talk, Table Talk: A Design of Ratio and Proportion as Classroom Parallel Events (Dor Abrahamson); (2) Generalizing the Context and Generalising the Calculation (Janet Ainley); (3) Interview…

These conference proceedings include two invited lectures, three working group reports, three topic group reports, two Ad Hoc group reports, a round table report, a list of participants, and a list of previous proceedings. The invited lectures were: "Values in Mathematics Education" (Ubiratan D'Ambrosio) and "Remarks on…