Introduction:
When it comes to revising and assessing one's understanding, there are two approaches that can be taken - using self-assessment tools or seeking external feedback. Both methods have their own advantages and disadvantages, and the choice between them depends on individual preferences and circumstances. In this response, we will explore these two approaches in detail to help you make an informed decision.

Self-Assessment Tools:
Self-assessment tools are resources that allow individuals to evaluate their own understanding and progress without external input. These tools can take various forms, such as practice tests, quizzes, flashcards, or even online platforms specifically designed for self-assessment. Here are some key points to consider when using self-assessment tools:

1. Flexibility: Self-assessment tools provide the flexibility to revise at your own pace and convenience. You can choose when and where to study, making it suitable for individuals with busy schedules or limited access to external feedback.

2. Independence: Self-assessment tools promote independent learning and critical thinking. They encourage individuals to reflect on their knowledge, identify areas of weakness, and develop strategies for improvement.

3. Cost-effective: Many self-assessment tools are freely available, making them a cost-effective option for those on a tight budget. Additionally, they eliminate the need for hiring tutors or seeking professional feedback, which can be expensive.

External Feedback:
Seeking external feedback involves obtaining input from others, such as teachers, peers, or subject matter experts, to assess your understanding. Here are some factors to consider when seeking external feedback:

1. Objective Evaluation: External feedback provides an objective evaluation of your understanding. It allows for an impartial assessment from someone who has expertise in the subject, which can help identify blind spots or misconceptions that you may not be aware of.

2. Validation: External feedback can validate your understanding and boost your confidence. Positive feedback from knowledgeable individuals can reinforce your knowledge and indicate that you are on the right track.

3. Constructive Criticism: Feedback from external sources can offer constructive criticism, highlighting areas where improvement is needed. This can help you focus your revision efforts on specific topics or concepts that require more attention.

Conclusion:
In conclusion, both self-assessment tools and external feedback have their own merits. Self-assessment tools provide flexibility and independence, while external feedback offers objective evaluation and constructive criticism. It is advisable to strike a balance between the two approaches, utilizing self-assessment tools for regular practice and seeking external feedback when you need an expert opinion or validation of your understanding. By combining these approaches, you can enhance your learning experience and improve your overall understanding of the subject matter.