אלה פקודי המשכן משכן העדות…(פקודי לח:כא)

The heads of the community of Vilna wanted to instate a rule that no Balei Darshanim – speakers could step into their Beis Medrash to give a speech, as it disturbs those delivering Torah classes.  When the Vilna Gaon zt’l heard about it, he summoned the heads of the community and told them: “Why was the Mishkan called by the name משכן? Since Hashem rested his Shechina – divine presence there since the Luchos were encased in the Aron.  The same is with a Beis Medrash, which is called a “בית המדרש” because of the “דרשות” – speeches that devout Yidden deliver there and arouse the Yidden to do teshuvah and obtain Yiras Shamayim.  And if speeches won’t be held, then it cannot be reckoned as a Beis Medrash.”