“…For example, Brown and Green (2009) calculated time spent reading discussions by extracting the average number of words per discussion and then multiplying it by 180 words per minute (which was obtained empirically). The challenge with this approach is in its inability to detect shallow reading and skimming (i.e., reading that is faster than 6.5 words per second) (Hewitt, Brett, & Peters, 2007), as done in similar studies (Oztok, Zingaro, Brett, & Hewitt, 2013;Wise, Speer, et al, 2013;Wise, Zhao, et al 2013b) that estimated timeon-task from trace-data. Some studies also used self-reported data on the amount of time students spent using the system (e.g., García-Martín & García-Sánchez, 2013;Hsu & Ching, 2013;Romero & Barbera, 2011), and this approach raises an additional set of reliability challenges (Winne & Jamieson-Noel, 2002).…”