diff --git a/sections.html b/sections.html
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+++ b/sections.html
@@ -24,13 +24,19 @@
             </ul>-->
         </p>
 
-        <h2 class="title" id="sec1">Section 3: Classification</h2>
+        <h2 class="title" id="sec4">Section 4: Neural Networks</h2>
+        <p class="head-subtitle">Tuesday, February 21</p>
+        <ul class="lists">
+            <li><a href="sections/sec04/04.pdf" target="_blank">PDF</a></li>
+        </ul>
+        
+        <h2 class="title" id="sec3">Section 3: Classification</h2>
         <p class="head-subtitle">Monday, February 13</p>
         <ul class="lists">
             <li><a href="sections/sec03-classification/03.pdf" target="_blank">PDF</a></li>
         </ul>
         
-        <h2 class="title" id="sec1">Section 2: Nonparametric Regression, Probabilistic Linear Regression, MLE, & Model Selection</h2>
+        <h2 class="title" id="sec2">Section 2: Nonparametric Regression, Probabilistic Linear Regression, MLE, & Model Selection</h2>
         <p class="head-subtitle">Monday, February 6</p>
         <ul class="lists">
             <li><a href="sections/sec02/02.pdf" target="_blank">PDF</a></li>