Productive Failure is an instructional approach in which students engage in problem-solving attempts prior to instruction. The Productive Failure approach has been found to be more supportive for conceptual knowledge acquisition during subsequent instruction compared to a direct-instruction condition in which students receive instruction first followed by problem solving. Failing at problem-solving attempts prior to instruction is considered to prepare students to better understand the concepts underlying the problem. However, it is an open question whether students need to fail themselves to be effectively prepared for subsequent instruction. We therefore compared the effectiveness of two alternative preparatory activities: Students either engaged in problem-solving attempts themselves or were shown problem-solving attempts of another student. This experimental variation allows to show the necessity of own failure for the effectiveness of the PF approach. The results indicated that the two conditions were equally effective at preparing students for subsequent instruction.