Entity relationship diagrams
ERDs show the relationship between classes of data, or data entities. Unified Modelling Language (UML) is a common language to use to show the relationships between classes or entities. Concepts of one-to-one, one-to-many or many-to-many is used here.
Data models are good concept sources for having discussions with stakeholders.
Data dictionary, not often used, can be developed to document the definition of specific fields of data, like organization or business title, and could also contain information about how the data will be formatted, length of the data that can be stored and how the field is related to other objects found or sourced into the warehouse.
Data scientist is a great resource and stakeholder, if you have one within your organization.
Great conclusion to the morning session before we break for lunch and get into the actual working portion of the workshop in the afternoon.