In the field of mobile learning, very few studies focused on the interaction between varied types of instructional devices and different types of instructional messages. This study explored the effects of instructional devices (Desktop PC vs. PDA) and instructional messages (text-only vs. text with a simulation tool) on undergraduate Electronic Engineering students. Results showed that students expressed a significant higher intention to learn in a Desktop PC environment, not in the PDA (F[1,21]=17.32, p<0.05). Results also indicated that students who used a MATLAB simulation tool performed significant better scores on their learning achievement test than those who did not use it (F[1,21]=10.96. p<0.05). In addition, the students who used MATLAB expressed a significant higher intention to learn than those who did not use it (F[1,21]=41.86, p<0.05).