ALEKS (Assessment and LEarning in Knowledge Spaces) is a web-based intelligent tutoring system that uses adaptive questioning to determine what a student knows and doesn't know.  While students work through an ALEKS course they are occasionally reassessed to make sure that the students have retained the knowledge they previously learned.  ALEKS courses are exhaustive, so much so that if a student shows mastery in an ALEKS course they will be successful in their corresponding course at school. The ALEKS website is located at http://www.aleks.com/ . Provided below are some useful links for more information about ALEKS and some screenshots of the ALEKS interface.  

For a video tour of ALEKS click HERE

This is a screenshot of the ALEKS problem selection pie.  The further a student advances their mastery of a subtopic in their course, the more their pie will fill up.  This pie helps students visualize their progress through the ALEKS course.  

This is a screenshot of the ALEKS interface.