To determine the correct level of teaching related to the scenario presented in the question, we need to evaluate each option in the context of teaching aptitude.

1. Memory Level: This involves rote learning where the primary focus is on memorizing facts, definitions, and formulas. It does not emphasize understanding the underlying concepts or the ability to apply information.
2. Understanding Level: At this level, the teacher aims to help students comprehend principles and concepts. This involves using examples, positive and negative, to facilitate a deeper understanding of the subject matter. Presentations with examples are indicative of this level, as they help students relate to the content more effectively.
3. Reflective Level: This involves critical thinking and problem-solving skills. Students are encouraged to reflect on the material, question assumptions, and develop their own insights or conclusions. This is a more advanced level of thinking beyond just understanding.
4. Autonomous Development Level: This level focuses on helping students to become independent learners and thinkers. It involves self-directed learning techniques and is more advanced than the understanding level but typically not directly related to classroom presentations.

After reviewing the options, the level of teaching most aligned with using positive and negative examples to support a presentation is the Understanding Level. This approach is pivotal in ensuring students grasp the essence of the subject matter by relating concepts to real-life examples.

Therefore, the correct answer is Understanding Level.