In general, the most relevant tasks to your students - the ones due nearest in the future - will show up on their dashboards, and they can begin those tasks directly from there. However, sometimes your students might need to work on overdue tasks, or to review tasks that they had previously completed. They can find these in their Tasks page.
The first section will show upcoming tasks, and students will be able to either begin or continue tasks that are due in the future.
The second section will show past tasks. If the task is still active, and the student has not yet completed the task, they will be able to continue from where they left off. If the task has expired, or if the student has already completed the task, they will be able to review their work.