When Xander uses a pen and a napkin to draw a diagram to explain the layout of his new apartment to his sister, he is engaging in a form of interpersonal communication known as **visual communication**.
Here's why:
1. **Visual Communication**: Xander is using visual aids (the diagram) to convey information to his sister. Visual communication involves the use of images, diagrams, charts, or any visual elements to enhance the message being communicated.
2. **Benefits of Visual Communication**: Using visual aids can make complex information easier to understand and remember. In this case, Xander's diagram can provide a clear representation of the apartment layout, making it more accessible and comprehensible to his sister.
3. **Effective Communication Tool**: Visual communication can be especially effective when describing spatial relationships, layouts, or designs, as in the case of Xander explaining the apartment layout. It can help in minimizing misinterpretation and ensuring a clearer transfer of information.
Therefore, the type of interpersonal communication Xander is using when he starts to draw the diagram of his new apartment for his sister is **Visual Communication**.
