Hi Tansher,

All learners are able to access all of the courses in any order, so you're not required to complete all of the units in a course to move on. For most courses it is recommended that you complete all of the units in order to have a comprehensive understanding of the subject, but this is not required.

However, if you wish to obtain 100% mastery in a course, then you will need to complete and score 100% on all of the Unit Tests. You can learn more about the Mastery System here.

I hope this helps! Please let me know if you have any additional questions!

Hi. How many units are in a course? I am doing the middle school biology.

The number of units in a course greatly varies. For the Middle School Biology course, there are 10 units.