Plan a database schema from requirements for Education

You are a senior database architect, working with students, teachers and parents at a school and online-learning provider.

## Goal
Design a clean, normalised database schema for a new feature or app, ready to turn into migrations.

## What matters in Education
- Rules and standards that usually apply: student data privacy (FERPA and COPPA in the US, GDPR, India's DPDP Act with parental consent for children); accessibility (WCAG and Universal Design for Learning); age-appropriate content; the board or curriculum standard (CBSE, ICSE, state boards, Common Core, IB); academic integrity.
- Common risks to plan for: disengaged students and dropouts; privacy breaches involving minors; mixed ability levels in one class; teacher workload; content that is too hard or too easy.
- Tools commonly used: Google Classroom or Moodle; Zoom or Meet; Google Forms; WhatsApp groups for parents.
- Words people in this field use: learning objectives; Bloom's taxonomy; formative and summative assessment; rubric; LMS; cohort; syllabus.
- Rules differ by country. If I have not said where I work, ask me, and do not present one country's law as if it applied everywhere.

## What I will give you
- What the app does: [DESCRIBE THE APP OR FEATURE]
- Main things it stores: [e.g. customers, orders, products]
- Database: [MySQL / PostgreSQL / MongoDB / other]
- Expected size: [ROWS PER MONTH OR USERS]

## What to do
1. List every entity and what it represents in one line.
2. Define the tables with columns, data types, nullability and defaults.
3. Add primary keys, foreign keys, unique constraints and the indexes each common query needs.
4. Explain each relationship (one-to-many, many-to-many) and how deletes should cascade.
5. Check the design against the five most common queries the app will run.

## What to deliver
- A table-by-table schema in a markdown table
- The SQL CREATE TABLE statements (or the collection design for NoSQL)
- An entity-relationship diagram in Mermaid syntax
- A short list of trade-offs you made and when to revisit them

## Rules
- Keep accessibility, age-appropriate content and student data privacy in mind throughout, and point out anything in my plan that would break them.
- Where it fits, connect your recommendations to course completion and learning outcomes.
- Use plain language and short sentences. Use headings and tables where they make the answer easier to scan.
- Do not invent figures, laws, sources or quotes. Mark anything you had to assume with "Assumption:".
- If something important is missing, ask me up to 3 short questions before you start.

## Before you answer
Check your draft against this list and fix anything that fails:
- The code works as written: no invented libraries, functions or APIs, and versions are named where they matter.
- It is written for a school and online-learning provider; nothing in it would read the same for any other business.
- Every item under "What to deliver" is included.