diff --git a/files/buzzer.py b/files/buzzer.py
new file mode 100644
index 0000000..8f96584
--- /dev/null
+++ b/files/buzzer.py
@@ -0,0 +1,67 @@
+# buzzer.py
+from machine import Pin, PWM
+import time
+
+# === Global note frequencies (A4 = 440 Hz tuning) ===
+NOTES = {
+    "C3": 131, "D3": 147, "E3": 165, "F3": 175, "G3": 196, "A3": 220, "B3": 247,
+    "C4": 262, "D4": 294, "E4": 330, "F4": 349, "G4": 392, "A4": 440, "B4": 494,
+    "C5": 523, "D#5": 622, "D5": 587, "E5": 659, "F5": 698, "G5": 784, "G#5": 831, "A5": 880, "B5": 988,
+    "C6": 1047, "D6": 1175, "E6": 1319, "F6": 1397, "G6": 1568, "A6": 1760, "B6": 1976,
+}
+
+
+REST = 0  # constant for silence
+
+class Buzzer:
+    def __init__(self, pin=29):
+        self.pwm = PWM(Pin(pin))
+        self.pwm.duty_u16(0)
+
+    def _start(self, freq, duty=32768):
+        self.pwm.freq(freq)
+        self.pwm.duty_u16(duty)
+
+    def _stop(self):
+        self.pwm.duty_u16(0)
+
+    def tone(self, freq, duration=200, duty=32768):
+        """Play a single tone or rest."""
+        if freq == REST:
+            self._stop()
+            time.sleep_ms(duration)
+        else:
+            self._start(freq, duty)
+            time.sleep_ms(duration)
+            self._stop()
+
+    def sequence(self, tones):
+        """
+        tones: list of (note, duration) where note can be a string ("E4") or int frequency.
+        """
+        for note, dur in tones:
+            if note == REST:
+                self.tone(REST, dur)
+            elif isinstance(note, str):
+                self.tone(NOTES[note], dur)
+            else:
+                self.tone(note, dur)
+            time.sleep_ms(30)
+
+    def mario_theme(self):
+        notes = [
+            ("E4",125), ("E4",125), (REST,125), ("E4",125),
+            (REST,125), ("C4",125), ("E4",125), (REST,125),
+            ("G4",125), (REST,375), ("G3",125),
+            (REST,375), ("C4",125), (REST,250), ("G3",125),
+            (REST,250), ("E4",125), (REST,250), ("A5",125),
+            (REST,125), ("B5",125), (REST,125), ("A5",125),
+            ("G5",125), ("E5",125), ("G5",125), ("A5",125),
+        ]
+        self.sequence(notes)
+      
+
+    def wake_up(self):
+        notes = [("E4", 125), ("C4", 125), ("A5", 125)]
+        self.sequence(notes)
+
diff --git a/index.html b/index.html
index 318d46d..6ef876c 100644
--- a/index.html
+++ b/index.html
@@ -22,6 +22,7 @@
         <div class="max-w-8xl mx-auto px-4 py-4 flex space-x-6 select-none">
             <button class="tab-btn active text-blue-600" data-target="lesson1">Environment Setup</button>
             <button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson2">Uploading Code</button>
+            <button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson2b">Buzzer</button>
             <button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson3">Motors</button>
             <button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson4">Color Sensors</button>
             <button class="tab-btn text-gray-600 hover:text-blue-600 hidden" data-target="lesson5">I2C Multiplexing</button>
@@ -147,6 +148,85 @@
             </div>
         </section>
 
+        <!-- Lesson 2b (hidden initially) -->
+        <section id="lesson2b" class="lesson-content hidden">
+            <h1 class="text-3xl font-bold mb-6">Using the Buzzer</h1>
+
+            <div class="grid grid-cols-1 md:grid-cols-2 gap-6">
+
+                <!-- Step 1 -->
+                <div class="prose">
+                    <h2>Step 1: Wiring</h2>
+                    <p>The buzzer is a simple piezo speaker. We drive it with PWM from a single GPIO pin, so we only
+                        need signal and ground.</p>
+                    </br>
+                    <p><code>RP2040 GP29 ------ BUZZER +</code></p>
+                    <p><code>RP2040 GND ------- BUZZER -</code></p>
+                    </br>
+                    <p>By changing the PWM frequency we change the pitch of the sound. Higher frequency means a higher
+                        note.</p>
+                </div>
+                <div>
+                </div>
+
+                <!-- Step 2 -->
+                <div class="prose">
+                    <h2>Step 2: Coding</h2>
+                    <p>The code for the buzzer includes note frequencies and helpers for playing tones and sequences, so
+                        we'll upload this file to our device, or copy->paste the contents into a new file called
+                        buzzer.py.</p>
+                    </br>
+                    <p><a href="files/buzzer.py">buzzer.py</a></p>
+                    </br>
+                    <p>We initialize the buzzer with <code>buzz = buzzer.Buzzer()</code>. By default it uses pin 29.
+                    </p>
+                    </br>
+                    <p>We play a list of notes with
+                        <code>buzz.sequence([(freq, duration), ...])</code>. Each pair is a frequency in Hz and a
+                        duration in milliseconds.
+                    </p>
+                </div>
+                <div>
+                    <pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
+# main.py
+import time
+import buzzer
+
+buzz = buzzer.Buzzer()
+buzz.sequence([(440, 200),
+               (880, 200)])
+</code></pre>
+                </div>
+
+                <!-- Step 3 -->
+                <div class="prose">
+                    <h2>Step 3: Adding more notes</h2>
+                    <p>The data we pass to buzz.sequence([]) in the square brackets is called an array.</p>
+                    <p>You can add as many (note, duration) pairs as you want..</p>
+                </div>
+                <div>
+                    <pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
+# main.py
+import buzzer
+import time
+
+buzz = buzzer.Buzzer()
+
+# Play named notes
+buzz.sequence([(440, 200),
+               (880, 200),
+               (600, 100),
+               (1200, 100)])
+time.sleep(2)
+
+# Or use a built-in tune
+buzz.mario_theme()
+</code></pre>
+                </div>
+
+            </div>
+        </section>
+
         <!-- Lesson 3 (hidden initially) -->
         <section id="lesson3" class="lesson-content hidden">
             <h1 class="text-3xl font-bold mb-6">Driving a Motor</h1>