The presented study aimed at examining the effect of ARCS model on the Achievement Motivation (AM) and Academic Achievement (AA) of the tenth grade students. One hundred and thirteen tenth grade students (28 male, 85 female), divided into two groups (experimental = 50, control = 63), studied a unit about magnetism with the use of two different methods, an ARCS model and a traditional model for 2 weeks. Two instruments were used, a Motivation Achievement Test (MAT) and an Achievement Test (AT). The results showed that there were significant differences on the MAT and AT due to the implemented ARCS motivational model.