Hi Katherine

Totara has a  'Site logs' report  available under the report builder that records access by users. This can be filtered and exported to a spreadsheet to show access at an user activity level. 

This records the time of the action rather than the duration - so would have to assume that the user was working on the activity until the next action in the log occured for the user. 

If it is just course completion duration then in version 10 there were two columns added to the Course completion report 

• time to complete (since start date)
• time to complete (since enrolment date) 

that can be added to show this information. 

The problem with these values is that it is only showing the time the user has accessed content not whether they are actually working on it.

regards