Moodle keeps tracks of user activity in Moodle.  To view information from the Moodle logs, click on Reports at the top of the course page.   There are a variety of reports on Moodle activity that are available.

Dates - lists all of the course activities that have a date associated with them (ie. course start date, due dates, etc.)

Logs - reports on all activity within the course

Live Logs - quick report on course activity in the last hour

Activity report - number of views for each activity in the course.  Does not include any user information.

Course participation - report on if students view or post to a specific activity within the course over the past week. 

Activity completion - check boxes for each course activity for each participant

Roster - course participants with photos (if available)

Statistics - Nothing currently