Add multilingual language and systems learning tracks

en/csharp-practice-20261101/lesson-1/lesson.html

@@ -0,0 +1,12 @@
+<!doctype html><html lang="en"><meta charset="utf-8"><title>Collections and repeated work</title><h1>Collections and repeated work</h1><p>15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.</p><p>A collection stores related values. The loop visits 1, 2, and 3, updating the total from 0 to 1, then 3, then 6. Record this trace rather than guessing. Identify the first and last valid positions in this language: Pascal can declare a 1-based array, while many other examples use zero-based containers. Add another value and update the bounds correctly. Explain what an empty collection should produce.</p><p><code>Main</code> is the entry method inside <code>Program</code>. <code>Console.WriteLine</code> prints a line. A class instance can have several references to the same object; assigning a reference does not clone the object.</p><pre><code class="language-csharp">using System;
+using System.Collections.Generic;
+class Program {
+
+    static void Main() {
+        int[] minutes = {1, 2, 3};
+        int total = 0;
+        foreach (int value in minutes) total += value;
+        Console.WriteLine(total);
+    }
+}
+</code></pre><p><strong>Expected result:</strong> <code>6</code></p><h3>Practice and evidence</h3><p>Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.</p><p><a href="https://learn.microsoft.com/en-us/dotnet/csharp/tour-of-csharp/">Language reference</a></p></html>

en/csharp-practice-20261101/lesson-1/main.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+class Program {
+
+    static void Main() {
+        int[] minutes = {1, 2, 3};
+        int total = 0;
+        foreach (int value in minutes) total += value;
+        Console.WriteLine(total);
+    }
+}