This lecture explains the design model for managing interactions in a mini-project where small games are programmed with actors interacting. The instructor provides insights on categorizing actors into interactors and interactables, defining specific methods for each, and delegating interaction management to a specific handler class. The lecture emphasizes the importance of minimizing code modifications when adding new actors by delegating interaction management to a specific handler class. It also covers the implementation of interaction methods for interactors and interactables, ensuring that interactions are managed efficiently and effectively.