We've set up our Kahn Academy accounts using student CPS gmail accounts. I have added myself as a coach for each student according to their math block and they currently have two assignments that we have worked on in class together. I will use the Kahn Academy unit tests as TASK scores when it makes sense.
One of the many great things about Kahn Academy is the ability to re-try concepts (practice and tests) as many times as they want and to preview or work ahead of the class. Although I typically encourage students to stay within the course work we are doing in class as it also tracks the number of attempts and percentages for each attempt, some of our students could use the challenge and enrichment.
Take a moment and log onto Kahn Academy with your student and check out the units in the 5th grade course. You can add yourself as their coach too!