Upvote the post and this comment to show that you agree with me.

Yeah, they really do need a restart button on there. 

Hi Paurush!

Thanks for sharing your thoughts on the addition of the Start Over button to Course Challenges. We are always working to add features that improve our site, and we love getting input from our community.

I've passed your feedback along to the team and it will be part of our conversation as we plan the future of Khan Academy.

Thanks for helping improve Khan Academy!