Trailhead is a great tool for learning Salesforce and soft-skills. However, currently quiz type unit doesn't allow us to retake "Challenge". And we cannot copy and paste challenge quizzes directly. So I created a simple scraping app for Trailhead unit. You can easily copy and paste Trailhead quizzes by designating URL of a Trailhead unit. Have fun!
Trailhead Quiz Extractor - https://trailhead-quiz-extractor.herokuapp.com/