diff --git a/02-Discrete-Bayes.ipynb b/02-Discrete-Bayes.ipynb
index 0fef96f..7147b15 100644
--- a/02-Discrete-Bayes.ipynb
+++ b/02-Discrete-Bayes.ipynb
@@ -598,17 +598,17 @@
     "from ipywidgets import interact, IntSlider\n",
     "\n",
     "belief = np.array([.35, .1, .2, .3, 0, 0, 0, 0, 0, .05])\n",
-    "beliefs = []\n",
+    "perfect_beliefs = []\n",
     "\n",
     "for _ in range(20):\n",
     "    # Simon takes one step to the right\n",
     "    belief = perfect_predict(belief, 1)\n",
-    "    beliefs.append(belief)\n",
+    "    perfect_beliefs.append(belief)\n",
     "\n",
     "def simulate(time_step):\n",
-    "    book_plots.bar_plot(beliefs[time_step], ylim=(0, .4))\n",
+    "    book_plots.bar_plot(perfect_beliefs[time_step], ylim=(0, .4))\n",
     "    \n",
-    "interact(simulate, time_step=IntSlider(value=0, max=len(beliefs)-1));"
+    "interact(simulate, time_step=IntSlider(value=0, max=len(perfect_beliefs)-1));"
    ]
   },
   {
@@ -763,20 +763,20 @@
    ],
    "source": [
     "belief = np.array([1.0, 0, 0, 0, 0, 0, 0, 0, 0, 0])\n",
-    "beliefs = []\n",
+    "predict_beliefs = []\n",
     "    \n",
     "for i in range(100):\n",
     "    belief = predict_move(belief, 1, .1, .8, .1)\n",
-    "    beliefs.append(belief)\n",
+    "    predict_beliefs.append(belief)\n",
     "\n",
     "print('Final Belief:', belief)\n",
     "\n",
     "# make interactive plot\n",
     "def show_prior(step):\n",
-    "    book_plots.bar_plot(beliefs[step-1])\n",
+    "    book_plots.bar_plot(predict_beliefs[step-1])\n",
     "    plt.title('Step {}'.format(step))\n",
     "\n",
-    "interact(show_prior, step=IntSlider(value=1, max=len(beliefs)));"
+    "interact(show_prior, step=IntSlider(value=1, max=len(predict_beliefs)));"
    ]
   },
   {
@@ -1205,25 +1205,28 @@
     "    return priors, posteriors\n",
     "\n",
     "\n",
-    "def plot_posterior(posteriors, i):\n",
+    "def plot_posterior(hallway, posteriors, i):\n",
     "    plt.title('Posterior')\n",
     "    book_plots.bar_plot(hallway, c='k')\n",
     "    book_plots.bar_plot(posteriors[i], ylim=(0, 1.0))\n",
     "    plt.axvline(i % len(hallway), lw=5)    \n",
     "    \n",
-    "def plot_prior(priors, i):\n",
+    "def plot_prior(hallway, priors, i):\n",
     "    plt.title('Prior')\n",
     "    book_plots.bar_plot(hallway, c='k')\n",
     "    book_plots.bar_plot(priors[i], ylim=(0, 1.0), c='#ff8015')\n",
     "    plt.axvline(i % len(hallway), lw=5)    \n",
     "\n",
-    "def animate_discrete_bayes(step):\n",
-    "    step -= 1\n",
-    "    i = step // 2    \n",
-    "    if step % 2 == 0:\n",
-    "        plot_prior(priors, i)\n",
-    "    else:\n",
-    "        plot_posterior(posteriors, i)"
+    "def animate_discrete_bayes(hallway, priors, posteriors):\n",
+    "    def animate(step):\n",
+    "        step -= 1\n",
+    "        i = step // 2    \n",
+    "        if step % 2 == 0:\n",
+    "            plot_prior(hallway, priors, i)\n",
+    "        else:\n",
+    "            plot_posterior(hallway, posteriors, i)\n",
+    "    \n",
+    "    return animate"
    ]
   },
   {
@@ -1259,7 +1262,7 @@
     "zs = [hallway[i % len(hallway)] for i in range(50)]\n",
     "\n",
     "priors, posteriors = discrete_bayes_sim(prior, kernel, zs, z_prob, hallway)\n",
-    "interact(animate_discrete_bayes, step=IntSlider(value=1, max=len(zs)*2));"
+    "interact(animate_discrete_bayes(hallway, priors, posteriors), step=IntSlider(value=1, max=len(zs)*2));"
    ]
   },
   {
@@ -1305,7 +1308,7 @@
     "zs = [1, 0, 1, 0, 0, 1]\n",
     "z_prob = 0.75\n",
     "priors, posteriors = discrete_bayes_sim(prior, kernel, zs, z_prob, hallway)\n",
-    "interact(animate_discrete_bayes, step=IntSlider(value=12, max=len(zs)*2));"
+    "interact(animate_discrete_bayes(hallway, priors, posteriors), step=IntSlider(value=12, max=len(zs)*2));"
    ]
   },
   {
@@ -1336,7 +1339,7 @@
    "source": [
     "measurements = [1, 0, 1, 0, 0, 1, 1]\n",
     "priors, posteriors = discrete_bayes_sim(prior, kernel, measurements, z_prob, hallway);\n",
-    "plot_posterior(posteriors, 6)"
+    "plot_posterior(hallway, posteriors, 6)"
    ]
   },
   {