The present article is based on a cloud-based course for teaching EFL writing skills to students majoring in information technology. The course methodology reflects recent theoretical views and empirical findings related to technology-based education. The effectiveness of the cloud-based course was tested through two experiments, on two different modules of the course: Summary writing and Writing for the web. Both experiments followed a pretest- immediate post-test-delayed posttest design with two experimental groups. The purpose of the experiments was to provide empirical data about the level of learning gain in relation to a 90% mastery threshold. In addition, the effectiveness of interactive vs. individual work on the level of mastery of the target skills was established in each experiment. Both approaches are suitable for technology-based instruction; however the majority of previous studies have examined the effectiveness of interactive work, whereas research comparing the two approaches is insufficient. The course effectiveness was established through paired t-test comparisons of students’ scores on the pre-, immediate, and delayed posttests. The results showed significant learning gains from the pre- to the immediate posttest and from the immediate to the delayed posttest. Students’ mastery of the target skills shifted towards above or close to the 90% mastery threshold. The comparison of the interactive and individual approaches through independent t-tests showed a significant priority for the interactive condition on the immediate and delayed posttests in both experiments. The post-experimental survey showed that the majority of the participants favored interactive work regardless of the condition they were in.