diff --git a/ipywidgets-tutorial.ipynb b/ipywidgets-tutorial.ipynb
index 4e04684..4013ce6 100644
--- a/ipywidgets-tutorial.ipynb
+++ b/ipywidgets-tutorial.ipynb
@@ -183,22 +183,21 @@
     "ax.set_ylim([-4, 4])\n",
     "ax.grid(True)\n",
     "\n",
-    "# generate x values\n",
+    "# generate x values and create placeholder plot\n",
     "x = np.linspace(0, 2 * np.pi, 100)\n",
-    "\n",
+    "scope = ax.plot(x, x, color='C0')\n",
     "\n",
     "def my_sine(x, w, amp, phi):\n",
     "    \"\"\"\n",
-    "    Return a sine for x with angular frequeny w and amplitude amp.\n",
+    "    Return a sine for x with angular frequency w and amplitude amp.\n",
     "    \"\"\"\n",
     "    return amp*np.sin(w * (x-phi))\n",
     "\n",
     "\n",
     "@widgets.interact(w=(0, 10, 1), amp=(0, 4, .1), phi=(0, 2*np.pi+0.01, 0.01))\n",
-    "def update(w = 1.0, amp=1, phi=0):\n",
-    "    \"\"\"Remove old lines from plot and plot new one\"\"\"\n",
-    "    [l.remove() for l in ax.lines]\n",
-    "    ax.plot(x, my_sine(x, w, amp, phi), color='C0')"
+    "def update(w=1.0, amp=1, phi=0):\n",
+    "    \"\"\"Replace data of plot with new one\"\"\"\n",
+    "    scope[0].set_ydata(my_sine(x, w, amp, phi))\n"
    ]
   },
   {