By default when students first start on Sumdog they will be in Training mode. This is where they can do their diagnostic test and work through the skill plan.
The diagnostic test will help place the students in their ability level based on their diagnostic test score. They will need to be in Training mode to complete the diagnostic test. Here is more information on the diagnostic test.
Once the student had completed their diagnostic test they will start to work through the skill plan based on their diagnostic test score. Here is more information on what the diagnostic test score means.
To progress through the skill plan the student will do so while in Training mode.