diff --git a/book.json b/book.json
new file mode 100644
index 0000000..3c6d55c
--- /dev/null
+++ b/book.json
@@ -0,0 +1,3 @@
+{
+    "plugins": ["exercises"]
+}
\ No newline at end of file
diff --git a/kapitel-3.md b/kapitel-3.md
index 30754ae..6c68586 100644
--- a/kapitel-3.md
+++ b/kapitel-3.md
@@ -1,4 +1,24 @@
 # Kapitel 3: Übertragungsprotokolle und Datentransformationen \(02.11.2017\)
 
+{% exercise %}
+Define a variable `x` equal to 10.
 
+{% initial %}
+var x =
+
+{% solution %}
+var x = 10;
+
+{% validation %}
+assert(x == 10);
+
+{% context %}
+// This is context code available everywhere
+// The user will be able to evaluate `exposedVar`
+var exposedVar = 3;
+// ... or call `exposedFunction`
+function exposedFunction {
+    return 3;
+}
+{% endexercise %}