Generate a full detail guide on the study techniques of 'Spaced Repetition' and 'Active Recall.' The guide should be educational and practical. It must include: 1. A simple explanation of the science behind why these methods work (e.g., the forgetting curve). 2. A detailed, step-by-step guide on how to implement Active Recall in your studies. 3. A section on how to use Spaced Repetition with digital flashcard apps (like Anki) or a physical Leitner box system. 4. Common mistakes to avoid when using these techniques. Please include a supportive disclaimer.