Why is my Table / Spreadsheet in Lt not editable?

The Table and Spreadsheet Panels within Lt exist in both the Basic Category and the Question Category:

A Basic Table or Spreadsheet is a read-only panel as far as the Student Protocol is concerned. These can be used to display example or model results:

A Question Table or Spreadsheet will allow Students to edit the Table / Spreadsheet in question to tabulate their own values:

You can easily differentiate between them as a Student: editable Tables / Spreadsheets will have controls beneath them.