Studies incorporating technology into the teaching of trigonometry, although sparse, have demonstrated positive effects on student achievement. The optimal sequence for integrating technology with teacher-led mathematics instruction has not been determined. Our research investigated whether technology has a greater impact on student achievement and attitudes if it is implemented before or after whole class teaching. The curriculum context of the study was a set of learning objects (CLIPS: Trig) designed to support student learning of transformations of trigonometric functions. The software includes functional features identified in prior research: it relieves students of the tedium of creating graphs by hand; sliders give students control of the simulations within program parameters; there are easy transitions between algebraic and graphic representations; the environment is dynamic; animation and visualization are included with graphing functions. Twenty Canadian classrooms (N = 489 grade 11-12 students, aged 17-18 years) were randomly assigned to two instructional sequences: CLIPS: Trig followed by whole-class teaching (CLIPS early treatment) and whole-class teaching followed by CLIPS: Trig (CLIPS late treatment). We found that in the pre-test to post-test comparisons, students who experienced CLIPS: Trig after whole-class teaching of core concepts learned more than students who began the unit with technology-supported simulations. However, there were no statistically significant differences in the pre-test to delayed post-comparisons. Beginning the trigonometry unit with CLIPS: Trig enhanced the impact of whole-class teaching, while beginning with whole-class teaching enriched students' technology experience. The findings suggest that a tight integration of whole-class and technology-assisted instruction is preferable.