Hi,
There are little circles on the left navigation that you can use to help keep track of your progress through the course.
When you start an activity, these circles are empty. As you make progress, these circles become partially filled, and they're completely filled when you move to the next activity. If you want to check if you've already completed an activity (in part or in full), look to these blue circles as your indicators.
It is true, however, that the actual answers you gave in each activity are not saved after you move on.
Hope that helps everyone, and thanks for participating!