Fix pedagogical issue: Don't show code examples before asking students to write code

PROBLEM: activity37 was showing complete code examples in Python, JavaScript,
Java, and C++ BEFORE asking students to write code themselves. This turns
learning into copy-paste practice.

FIXED:
- Hello World section: Removed multi-language code examples from content_blocks
- Variables section: Removed multi-language code examples from content_blocks
- Now explains CONCEPTS (what, why, how languages differ) without showing syntax
- Code examples remain in AI feedback for when students struggle or ask for help

PEDAGOGICAL APPROACH:
1. Explain the concept (stdout, variables, etc.)
2. Explain language differences conceptually (dynamic vs static typing)
3. Ask students to TRY writing code in THEIR language
4. Provide language-specific examples in AI FEEDBACK if they struggle

This way students actually have to THINK and LEARN, not just copy.

UPDATED CLAUDE.md:
- Added new pitfall: "Showing answers before questions"
- Guidance: Explain concepts in content_blocks, provide code examples in ai_feedback

Still validates perfectly with zero errors/warnings.

CLAUDE.md

@@ -694,6 +694,7 @@ feedback_tokens_for_ai: |
 | **Generic feedback** | "Good job!" isn't helpful | Reference specific parts of their answer |
 | **Dead-end paths** | User stuck, can't progress | Always provide a way forward (even if it's restarting) |
 | **Ignoring the rubric** | Global `tokens_for_ai_rubric` tells AI how to evaluate | Define it for consistency across steps |
+| **Showing answers before questions** | Users copy-paste instead of learning | Explain CONCEPTS in content_blocks, provide CODE EXAMPLES only in ai_feedback |
 
 ### Activity Development Workflow
 

research/activity37-programming-languages.yaml

@@ -174,30 +174,20 @@ sections:
     - ''
     - 'This is why understanding stdout matters - it''s not just "printing to the screen," it''s sending data to a stream that can go anywhere!'
     - ''
-    - '### How Different Languages Display Output'
-    - 'Every programming language has its own syntax, but they all accomplish the same goal. Here are examples across different languages:'
+    - '### How Languages Display Output'
     - ''
-    - '**Python:** Uses `print()` function'
-    - '```python'
-    - 'print("Hello, World!")'
-    - '```'
+    - 'Every programming language has its own syntax for displaying output to stdout:'
+    - '- Some use a `print()` function'
+    - '- Some use `console.log()`'
+    - '- Some use methods like `System.out.println()`'
+    - '- Some use stream operators like `<<`'
     - ''
-    - '**JavaScript:** Uses `console.log()` function'
-    - '```javascript'
-    - 'console.log("Hello, World!");'
-    - '```'
+    - 'Despite different syntax, they all accomplish the same goal: sending text to stdout.'
     - ''
-    - '**Java:** Uses `System.out.println()` method'
-    - '```java'
-    - 'System.out.println("Hello, World!");'
-    - '```'
+    - '**Important Concept:**'
+    - 'Text in quotes (like `"Hello, World!"`) is called a **string** - it represents text data that you want to display.'
     - ''
-    - '**C++:** Uses `std::cout` stream'
-    - '```cpp'
-    - 'std::cout << "Hello, World!" << std::endl;'
-    - '```'
-    - ''
-    - '**Key Concept:** Notice that while the syntax differs, each language has a way to send text to stdout. The quotes around "Hello, World!" indicate it''s a **string** (text data).'
+    - 'Now you''ll figure out how YOUR chosen language does it!'
     - ''
     - '### Now It''s Your Turn!'
     question: How do you display 'Hello, World!' to stdout in your chosen language? Write the complete code.
@@ -464,36 +454,26 @@ sections:
     - '**Good names:** `user_name`, `total_score`, `isActive`, `playerHealth`'
     - '**Bad names:** `x`, `temp`, `asdf`, `thing1`'
     - ''
-    - '### How to Create Variables in Different Languages'
+    - '### How Languages Handle Variables'
     - ''
-    - '**Python (dynamically typed):**'
-    - '```python'
-    - 'name = "Alice"    # Create variable and assign value'
-    - 'print(name)        # Display the variable''s value'
-    - '```'
+    - 'Every programming language has its own syntax for creating variables, but they all follow the same basic pattern:'
+    - '1. Give the variable a name'
+    - '2. Use an assignment operator (usually `=`)'
+    - '3. Provide a value'
     - ''
-    - '**JavaScript (dynamically typed):**'
-    - '```javascript'
-    - 'let name = "Alice";     // Declare with let'
-    - 'console.log(name);      // Display'
-    - '```'
+    - '**Important Language Difference:**'
     - ''
-    - '**Java (statically typed):**'
-    - '```java'
-    - 'String name = "Alice";           // Must specify type'
-    - 'System.out.println(name);        // Display'
-    - '```'
+    - '**Dynamically typed languages** (like Python, JavaScript, Ruby):'
+    - '- You just name the variable and assign a value'
+    - '- The language automatically figures out the type'
+    - '- Simpler syntax, more flexible'
     - ''
-    - '**C++ (statically typed):**'
-    - '```cpp'
-    - 'std::string name = "Alice";      // Must specify type'
-    - 'std::cout << name << std::endl;  // Display'
-    - '```'
+    - '**Statically typed languages** (like Java, C++, C#, Go):'
+    - '- You must specify the data type when creating a variable'
+    - '- Example: declare that `name` will store a String'
+    - '- More verbose, but catches type errors early'
     - ''
-    - '### Key Differences'
-    - '**Dynamically typed languages** (Python, JavaScript, Ruby): You don''t declare the type. The language figures it out automatically.'
-    - ''
-    - '**Statically typed languages** (Java, C++, C#, Go): You must specify the type (String, int, etc.) when creating a variable.'
+    - 'You''ll use YOUR language''s specific syntax to create variables!'
     - ''
     - '### The Assignment Operator'
     - 'The `=` sign is the **assignment operator**. It means "assign the value on the right to the variable on the left."'