Despite its unquestionable interest from a theoretical and practical point of view, so far there has been little research on online reading and there is a lack of attention paid to this topic in most European educational institutions. In particular, primary and secondary school teachers are not adequately trained on how and when to intervene to support students' proficiency in the online reading comprehension. After presenting a rationale demonstrating why students may struggle with online reading comprehension and the importance to adopt a self-regulated reading, this study proposes a Teacher's Guide that could support late primary and secondary school teachers in planning online reading lessons with the Think-Aloud (TA) metacognitive technique.