Hello Donielle! My name is Lisa Krueger and I am a Khan Academy Ambassador teaching in Chicago. It really depends on the student and the subject area. As US History can be little dense and consists of over 300 skills it might take longer than another subject area. Also, Khan Academy is designed for students to work at their own pace and using a schedule might force the student to work at a faster pace than they would normally work at. In the past I used % of mission completed as a goal. Hopefully that helps. Please let me know if you have further questions, comments, or suggestions. Thank you for posting and Good Luck!

Thanks Lisa!  I guess what I am wondering though, is it reasonable for a high school student to complete US History in the scope of a school year and approximately how much time would he need to dedicate to accomplish that?

Hello Donielle! Yes, it would be reasonable for a student to complete the curriculum in a year. I have found the Khan Academy missions and subjects are designed for the average user to complete in 9-10 months (school year) when practicing about an hour a day. Hopefully this helps. Thank you for posting.