It certainly was not frontal teaching, but it was not participatory or collaborative either. Indeed, the manner in which Hashem instructed Moshe the majority of Torah has not been categorized or described, to my knowledge, in the annals of modern education. Rashi, noting an unusual construct in the last pasuk of our parsha, comments that Moshe listened in to Hashem talking to Himself.
This "fly on the wall" approach to study is recorded in the last pasuk of our parsha. Moshe, when called into the Ohel Moed (7:89), would hear Hashem "me'daber", which Rashi explains is a form of "misdaber", and thus translates as, "He heard the Voice uttering itself". Rashi further explains that it is out of reverence for the Most-High God that the Torah describes it as "The Voice speaking to itself", and Moses listening in.
As strange as it seems, it is quite easily appreciated by students of the Talmud and the Yeshiva Torah Tapestry of all times. After all, we, too, "listen in" to the debates of Beis Hillel and Beis Shammai, Rav and Shmuel, Rava and Abayei, Rambam and Raavad, the Ketzos and the Nesivos, Rav Moshe and Rav Henkin. And whereas this style of learning is charming and engaging, it so often strikes us as terribly inefficient. That is why it is so incredibly important to understand that Ravina and Rav Ashi, when writing the text of the Talmud, were following the style that Hashem initiated as He taught Moshe in the desert. It is Chazal once again following the style and format of the Almighty.
Human experience gives us an insight into the "eavesdropping" style of our daily Torah regimen. The "eavesdropper" or the "fly on the wall" knows, with every silenced and bated breath, that he is in a place that is beyond where he ought to be. The students of Hashem's Torah come to realize that we are far from deserving, or capable, of fully engaging with the word of Hashem, nor the repartee of Rav and Shmuel, nor even the crosstalk of the Torah giants and sages of any time.
It is this cumbersome style that reifies for us the precious privilege we have been gifted to behold and to delve into every Rashi and every Tosfos. May we all be blessed the yishuv hada'as to appreciate this gift to the best of our abilities.