Which element is part of Gagne's nine events of instruction?

The correct answer is presenting stimuli clearly, which is one of Gagne's nine events of instruction. This principle emphasizes the importance of clearly conveying the material to learners in a manner that captures their attention and facilitates understanding. In Gagne's model, presenting stimuli involves using various formats and strategies to ensure that the content is accessible and engaging, allowing students to grasp concepts effectively.

By focusing on clear presentation, educators are able to make the instructional material relevant and interesting, which enhances retention and comprehension. This element also lays the groundwork for subsequent instructional events, such as encouraging learners to acquire and apply new knowledge.

The other choices reflect aspects that do not align with Gagne’s principles. Providing immediate rewards might be effective in certain motivational contexts but is not a formal event in Gagne's framework. Summarizing content without assessment does not aid in ensuring that learners have adequately understood the material, as assessment is a critical part of reinforcing learning. Limiting collaboration among learners runs contrary to the idea of fostering an engaging and interactive learning environment, which is beneficial for overall educational experiences.