Voice-Activated Study Assistants

Design a voice-activated AI assistant that can help students prepare for exams by verbally answering their study-related questions and conducting quizzes. Include features for:

1. Responding to questions on [subject] with quick and accurate explanations.
2. Generating practice questions for the [subject] and quizzing the student verbally, providing instant feedback.
3. Summarizing complex topics into easy-to-understand points.
4. Customizing quizzes based on the student's progress and areas needing improvement.

Consider user-friendly interaction, personalization, and adaptability in your solution. Describe how the assistant would function and engage with students effectively.