An interesting study and clear written paper! However, I have several suggestions:
Knowing whether a person uses electronic devices during classroom is not the same as knowing the person was distracted. Authors should discuss this aspect and incorporate prior literature.
Authors should instead leave out all remarks/background concerning new, alternative teaching methods as their study focused on a tradiditional lecture. (e.g., it is not necessary to mention the Khan Academy).
In my opinion it is a problem that the authors chose a cross-sectional design. It would be better to ask students after every single lecture in a semester whether they used electronic devices during that lecture and the assess performance in the topic of the lecture in the end of the semester.
Furtmermore, the post-session questionnaire can be problematic as students answer questions on aspects they learned (or should have learned) during the lecture AND questions regarding their engagement of electronic activities during the lecture at the same time. Thus, students might form their personal hypothesis on the research question that was focused on with the questionnaire and answers might be biased.
Were there any control questions (e.g., How distracted did you feel?) -- see 1 in the basic reporting area.
Validity of the findings
The findings/results would be much more valid if engagement in electronic activities could be assessed objectively and/or long-term...
As I mentioned in the experimental design section, it could be that results are biased -- the result that males who were distracted outperformed females who were distracted, in particular as males might overestimate their smartphone, iPad use.
Comments for the author
I still think that the study is interesting and authors could improve the paper by discussing the critical aspects I mentioned in the areas above.