The transition to the "active" phase—usually starting around lesson 50—is where the method proves its depth. Here, the learner is asked to translate the Serbian sentences back into German, relying on memory and structural understanding. This "back-translation" technique is an old-school method that has recently been validated by polyglots as highly effective for cementing syntax. The PDF format enhances this utility; learners can easily cover the German text with their hand or a digital mask, testing their recall without flipping frantically through pages as one might with a physical book.