I have an advice for what regards the full tests available on Khan Academy. When I practice for the test I like to print the Reading part, while letting play in background the correspondent online section, and complete it by hand so that I can train for what it will be like on actual test day. Unfortunately, after finishing the whole test my score is 400, because I answered the questions on my questions sheet and, therefore, the website can't record my mistakes and areas where I should train even though my actual score is 1210 (calculated manually). That's why I would suggest to add the opportunity to edit your score on Khan Academy so that this type of problem can be overcome and people can manually select the choices they had previously made on the test, making it easier to progress availing of the website.