diff --git a/pages/activators-vs-repressors.md b/pages/activators-vs-repressors.md
new file mode 100644
index 0000000..b0b13b3
--- /dev/null
+++ b/pages/activators-vs-repressors.md
@@ -0,0 +1,7 @@
+<extends template="layouts/base.html" title="Choosing Between Activators & Repressors"></extends>
+
+<nav-links back="/hill-functions.html"></nav-links>
+
+# Choosing Between Activators & Repressors
+
+<nav-links back="/hill-functions.html"></nav-links>
\ No newline at end of file
diff --git a/pages/activators.md b/pages/activators.md
new file mode 100644
index 0000000..28298bb
--- /dev/null
+++ b/pages/activators.md
@@ -0,0 +1,7 @@
+<extends template="layouts/base.html" title="Activators"></extends>
+
+<nav-links back="/repressors.html" next="/hill-functions.html"></nav-links>
+
+# Activators
+
+<nav-links back="/repressors.html" next="/hill-functions.html"></nav-links>
\ No newline at end of file
diff --git a/pages/hill-functions.md b/pages/hill-functions.md
new file mode 100644
index 0000000..aa1b7f6
--- /dev/null
+++ b/pages/hill-functions.md
@@ -0,0 +1,7 @@
+<extends template="layouts/base.html" title="Ultrasensitivity & the Hill Function"></extends>
+
+<nav-links back="/activators.html" next="/activators-vs-repressors.html"></nav-links>
+
+# Ultrasensitivity & the Hill Function
+
+<nav-links back="/activators.html" next="/activators-vs-repressors.html"></nav-links>
\ No newline at end of file
diff --git a/pages/index.html b/pages/index.html
index 1ef1f74..3eddbc3 100644
--- a/pages/index.html
+++ b/pages/index.html
@@ -26,6 +26,13 @@
     <div class="fade fade5">
         <section-link href="/concepts.html">1. Concepts of Biocircuits</section-link>
         <section-link href="/simplest-circuit.html">2. The Simplest Circuit</section-link>
+        <section-link href="/repressors.html">3. Repressors & Leaks</section-link>
+        <section-link href="/activators.html">4. Activators</section-link>
+        <section-link href="/hill-functions.html">5. Ultrasensitivity & the Hill Function</section-link>
+        <section-link href="/activators-vs-repressors.html">6. Choosing Between Activators & Repressors</section-link>
+        <div class="under-construction">
+            More Sections Under Construction
+        </div>
     </div>
 </section>
 
@@ -93,4 +100,22 @@
 		font-style: italic;
 		margin-top: -10px;
 	}
+
+    .under-construction {
+        padding: 10px;
+        margin-top: 10px;
+        margin-bottom: 10px;
+        text-transform: uppercase;
+        color: inherit;
+        border: 2px solid;
+        opacity: 0.9;
+        text-align: center;
+        background: repeating-linear-gradient(
+            45deg,
+        rgba(0, 0, 0, 0),
+        rgba(0, 0, 0, 0) 10px,
+        rgba(0, 0, 0, 0.1) 10px,
+        rgba(0, 0, 0, 0.1) 20px
+        );
+    }
 </style>
\ No newline at end of file
diff --git a/pages/repressors.md b/pages/repressors.md
new file mode 100644
index 0000000..b238fc2
--- /dev/null
+++ b/pages/repressors.md
@@ -0,0 +1,7 @@
+<extends template="layouts/base.html" title="Repressors & Leaks"></extends>
+
+<nav-links back="/simplest-circuit.html" next="/activators.html"></nav-links>
+
+# Repressors & Leaks
+
+<nav-links back="/simplest-circuit.html" next="/activators.html"></nav-links>
\ No newline at end of file
diff --git a/pages/simplest-circuit.md b/pages/simplest-circuit.md
index 49abf61..7864f40 100644
--- a/pages/simplest-circuit.md
+++ b/pages/simplest-circuit.md
@@ -1,6 +1,6 @@
 <extends template="layouts/base.html" title="The Simplest Circuit"></extends>
 
-<nav-links back="/concepts.html"></nav-links>
+<nav-links back="/concepts.html" next="/repressors.html"></nav-links>
 
 # The Simplest Circuit
 
@@ -96,7 +96,7 @@ Here's a graph to play with:
 
 Onwards!
 
-<nav-links back="/concepts.html"></nav-links>
+<nav-links back="/concepts.html" next="/repressors.html"></nav-links>
 
 <script>
     plot('#concentration-graph', (beta, gamma) => `(${beta}x)/${gamma}`, ['#beta', '#gamma'])