Change Display Order of Apps in App Store?

Does anyone know of a way to change the order in which your apps appear in the App Store?

We've got a series of eight apps, (four brand new and four that have been in the store for several months).  The apps are educational and follow a course from elementary to more advanced, (Unit 1 app most basic, Unit 4 app most advanced). 

Is there a way to force the Unit 1 app to be displayed first and foremost ahead of the others?

Thanks for any suggestions!