diff --git a/notebooks/basics/single-systems.ipynb b/notebooks/basics/single-systems.ipynb
index 1cd048018..951923474 100644
--- a/notebooks/basics/single-systems.ipynb
+++ b/notebooks/basics/single-systems.ipynb
@@ -1518,7 +1518,16 @@
     "scrolled": true
    },
    "source": [
-    "(*** Interactive widget here.)"
+    "<!-- ::: q-block -->\n",
+    "\n",
+    "### Circuit sandbox\n",
+    "\n",
+    "    q-circuit-sandbox-widget(goal=\"circuit-sandbox\")\n",
+    "        .availableGates H X Z Y T S\n",
+    "        .instructions Drag the gates down onto the circuit to see how they transform the qubit.\n",
+    "        .explanation The 'matrix' display shows the unitary matrix of the circuit (i.e. all the gates' unitaries multiplied together). The 'state vector' display shows the state of the qubit after the gates act on it.\n",
+    "\n",
+    "<!-- ::: -->"
    ]
   },
   {