---
name: accessibility-readability
description: Ensure textbook content is accessible, readable, and understandable for learners of all skill levels. Use when reviewing content for clarity, adding explanations for beginners, or improving content accessibility.
---

# Accessibility & Readability Skill

## Instructions

### 1. Reading Level Guidelines

| Audience | Flesch Score | Characteristics |
|----------|--------------|-----------------|
| Beginner | 60-70 | Short sentences, common words, many examples |
| Intermediate | 50-60 | Technical terms with definitions, moderate complexity |
| Advanced | 40-50 | Assumes prior knowledge, concise explanations |

### 2. Explain Technical Terms

**First mention** of any technical term MUST include:

```mdx
**ROS 2** (Robot Operating System 2) is a middleware framework that provides 
tools and libraries for building robot applications. Think of it as the 
"nervous system" that lets different parts of a robot communicate.
```

### 3. Glossary Integration

Create `docs/glossary.mdx` with all terms:

```mdx
## R

### ROS 2
**Robot Operating System 2** — A middleware framework for robotics development.
- **Used in**: Modules 1, 3, 4
- **Prerequisite for**: Understanding node communication
- **Related**: Topics, Services, Actions

### rclpy
**ROS Client Library for Python** — Python bindings for ROS 2.
- **Installation**: `pip install rclpy`
- **Import**: `import rclpy`
```

Link to glossary on first use:
```mdx
We'll use [ROS 2](/docs/glossary#ros-2) to control our robot.
```

### 4. Multi-Level Explanations

Provide layered depth for complex topics:

```mdx
## What is a ROS 2 Node?

### 🟢 Simple Explanation (Beginner)
A node is like a worker in a factory. Each worker (node) has one job, 
and they communicate by passing messages to each other.

### 🟡 Technical Explanation (Intermediate)
A node is an independent process that performs computation. Nodes 
communicate via topics (pub/sub), services (request/response), or 
actions (long-running tasks with feedback).

### 🔴 Deep Dive (Advanced)
Nodes are executables within a ROS 2 package. They use DDS (Data 
Distribution Service) for communication, with QoS (Quality of Service) 
policies controlling reliability, durability, and history.
```

### 5. Prerequisite Mapping

Every chapter must clearly state what knowledge is assumed:

```mdx
## 📋 Prerequisites

**Required Knowledge:**
- ✅ Basic Python (variables, functions, classes)
- ✅ Command line basics (cd, ls, mkdir)
- ✅ [Chapter 1.1 — Introduction to Physical AI](/docs/module-1/week-1-2/)

**Helpful but Optional:**
- ⭕ Linux system administration
- ⭕ Previous robotics experience

**You'll Learn Here:**
- 🆕 ROS 2 node creation
- 🆕 Publisher/subscriber pattern
```

### 6. Code Accessibility

Always explain code step-by-step:

```mdx
```python
# Step 1: Import the ROS 2 Python library
import rclpy
from rclpy.node import Node

# Step 2: Create a class that inherits from Node
class MyNode(Node):
    def __init__(self):
        # Step 3: Initialize the parent class with a node name
        super().__init__('my_node')  # 'my_node' is visible in ROS tools
        
        # Step 4: Log a message to confirm the node started
        self.get_logger().info('Node has started!')
```

**Line-by-line breakdown:**
| Line | Purpose |
|------|---------|
| `import rclpy` | Load the ROS 2 Python library |
| `from rclpy.node import Node` | Import the base Node class |
| `class MyNode(Node)` | Create our custom node |
| `super().__init__('my_node')` | Register with ROS 2 |
| `self.get_logger().info(...)` | Print to ROS 2 logging system |
```

### 7. Visual Learning Aids

For each major concept, include:

1. **Analogy** — Real-world comparison
2. **Diagram** — Visual representation
3. **Code** — Working example
4. **Exercise** — Hands-on practice

```mdx
## Understanding Topics

### 🎯 Analogy
Topics are like radio channels. Publishers broadcast on a channel, 
and any subscriber tuned to that channel receives the message.

### 📊 Diagram
```mermaid
graph LR
    P[Publisher] -->|broadcasts| T[/topic_name]
    T -->|receives| S1[Subscriber 1]
    T -->|receives| S2[Subscriber 2]
```

### 💻 Code Example
[See code block above]

### ✍️ Exercise
Create a publisher that sends your name every second.
```

### 8. Accessibility Standards

**Images:**
```mdx
![Diagram showing ROS 2 node communication with arrows between publisher and subscriber nodes](/img/ros2-nodes.svg)
```

**Color contrast:** Don't rely solely on color
```mdx
✅ Good: "The green checkmarks (✅) indicate success"
❌ Bad: "Green items are complete"
```

**Keyboard navigation:** Ensure all interactive elements are accessible

### 9. Progress Indicators

Help learners track their journey:

```mdx
## 📍 Your Progress

| Module | Status | Completion |
|--------|--------|------------|
| Module 1: ROS 2 | 🟢 Current | 60% |
| Module 2: Simulation | ⚪ Upcoming | 0% |
| Module 3: Isaac | ⚪ Upcoming | 0% |
| Module 4: VLA | ⚪ Upcoming | 0% |

**Estimated time to complete this chapter:** 45 minutes
```

### 10. Recap Sections

End each major section with a quick recap:

```mdx
## 🔄 Quick Recap

**What we covered:**
- ✅ Created a ROS 2 node using Python
- ✅ Published messages to a topic
- ✅ Subscribed to receive messages

**Key commands:**
```bash
ros2 run my_package my_node    # Run a node
ros2 topic list                 # List all topics
ros2 topic echo /topic_name    # View messages
```

**Common mistakes to avoid:**
- ❌ Forgetting to call `rclpy.init()` before creating nodes
- ❌ Not spinning the node (`rclpy.spin(node)`)
```

## Validation Checklist

- [ ] All technical terms defined on first use
- [ ] Glossary entries for domain-specific terms
- [ ] Multi-level explanations for complex topics
- [ ] Prerequisites clearly stated
- [ ] Code explained line-by-line for beginners
- [ ] Images have descriptive alt text
- [ ] Estimated reading time provided
- [ ] Quick recaps at section ends

## Definition of Done

- Content passes readability check for target audience
- All technical terms linked to glossary
- Beginner/intermediate/advanced sections where appropriate
- Every code block has explanatory comments
- Accessibility standards met (alt text, contrast, etc.)