“…Several important study limitations, such as small sample sizes, low response rates, and/ or low statistical power (*Chertok, Barnes, and Gilleland, 2013; *Dee and Jacob, 2012; *Henslee, Goldsmith, Stone, and Krueger, 2015;*Liu, Lo, and Wang, 2013;*Morgan and Hart, 2013;*Smedley, Crawford, and Cloete, 2015), studies of a single institution only (* Chertok, Barnes, and Gilleland, 2013;*Fenster, 2016), and lack of random assignment (* Morgan and Hart, 2013;*Schuetze, 2004) were cited in the reviewed articles. We also noted that the time that participants spent completing homework assignments was not taken into account (*Schuetze, 2004), skills or student outcomes were not measured (e.g., *Elander, Pittam, Lusher, Fox, and Payne, 2010;*Jackson, 2006), or skills may not be generalizable to other settings (e.g., *Chertok, Barnes, and Gilleland, 2013;*Landau, Druen, and Arcuri, 2002).…”