Welcome to BFSU: › Forums › Open Discussion › This topic has 0 replies, 1 voice, and was last updated 3 years, 6 months ago by Bernard Nebel. Viewing 0 reply threads Author Posts April 20, 2021 at 1:33 pm #8691 Bernard NebelKeymaster Thank you for pointing out that the convection current video for Lesson A-18 was no longer working. It has been replaced. Author Posts Viewing 0 reply threads You must be logged in to reply to this topic.