Students especially in large groups often have many questions they do not ask because they’re afraid to speak in front of others. Sometimes questions are also perceived as embarrassing. However, many of these questions are so fundamental that it would be valuable for the learning progress if the teacher could hear them and answer them for everyone. This can be achieved with a “back channel” where students can send questions and feedback to the teacher in a timely manner. This would then enable quick, targeted answers. This background communication runs permanently during an event and is integrated into the 'official communication' at intervals. For the technical implementation, mattermost and "Etherpad" are available at the TUHH. In zoom, group chat would also be possible, but here questions cannot be asked anonymously. In the Etherpad, any number of people can access a document at the same time and anonymously and enter their questions there at the specified place. The implementation of a backchannel in large courses is easier if somebody selects and bundles the incoming questions before the lecturer responds to them.