If you are using English Essentials, you can set a number of exercises students need to pass.
Select the start and end date, the number of exercises students need to pass and the modules the goal will apply to. Note: Students will have to complete the set number of exercises for each of the selected modules.
Finally, select the classes you want to set the goal for. Tick the 'Inform students' box to notify students of the new goal. They will see the goal in their profiles.