E-learning 108 e-learning 34 Students 31 human 29 Learning systems 23 COVID-19 21 article 18 Humans 14 Online learning 14 Teaching 14 controlled study 14 Deep learning 13 Education 13 female 13 male 13 human experiment 12 Article 11 Machine learning 11 adult 10 learning 10 Curricula 9 Engineering education 9 major clinical study 9 Computer aided instruction 8 Surveys 8 pandemic 8 Higher education 7 Virtual reality 7 coronavirus disease 2019 7 education 7