_:na139761bf71344fba750534542824366xb2
<http://schema.org/url>
<https://www.gravatar.com/avatar/c4c0ec064f18ab28ede07760684f757c?s=250&d=mm&r=x>
<https://rtalbert.org/how-much-research-has-been-done-on-flipped-learning-the-2021-update/>