Hi Sharon,
I cannot remember what Cornelius refers to in the training material and slides. When you work on project scope management, you will have to draft the project scope statement, WBS and WBS dictionary. This are all outputs from the Define Scope process. The project scope statement, WBS and WBS dictionary contribute to the scope baseline; specifically, their approved version gives you the scope baseline.
To double check specific definitions, I'd recommend the glossary at the end of the PMBOK Guide: I often found it useful!
Hope this helps,
Gabriella