When students first start on Sumdog they will be in Training mode. This is where they complete 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. You can find more information about the diagnostic test here - What is the diagnostic test?
Once the student had completed their diagnostic test, Training mode is used to work through the skill plan based on their diagnostic test score. Students must be in Training mode to progress through the skill plan.