diff --git a/02_Noise2Void/exercise.ipynb b/02_Noise2Void/exercise.ipynb
index 990a397..6a92097 100644
--- a/02_Noise2Void/exercise.ipynb
+++ b/02_Noise2Void/exercise.ipynb
@@ -231,7 +231,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "<div class=\"alert alert-block alert-success\"><h1><b>Checkpoint 1: What is N2V really doing?</b></h1>\n",
+    "<div class=\"alert alert-block alert-success\"><h1><b>Checkpoint 1: N2V masking</b></h1>\n",
     "</div>"
    ]
   },
@@ -389,16 +389,6 @@
     "careamist = CAREamist(source=training_config)"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "%load_ext tensorboard\n",
-    "%tensorboard --logdir logs/lightning_logs"
-   ]
-  },
   {
    "attachments": {},
    "cell_type": "markdown",
diff --git a/03_COSDD/exercise.ipynb b/03_COSDD/exercise.ipynb
index b8ef461..b781074 100644
--- a/03_COSDD/exercise.ipynb
+++ b/03_COSDD/exercise.ipynb
@@ -340,7 +340,7 @@
    "source": [
     "<img src=\"resources/explainer.png\"/>\n",
     "\n",
-    "COSDD is a Variational Autoencoder~\\cite{chenvariational} (solid arrows) trained to model the distribution of noisy images $\\mathbf{x}$. \n",
+    "COSDD is a Variational Autoencoder (solid arrows) trained to model the distribution of noisy images $\\mathbf{x}$. \n",
     "The autoregressive (AR) decoder models the noise component of the images, while the latent variable models only the clean signal component $\\mathbf{s}$.\n",
     "In a second step (dashed arrows), the \\emph{signal decoder} is trained to map latent variables into image space, producing an estimate of the signal underlying $\\mathbf{x}$.\n",
     "{\\bf b):}\n",
@@ -603,7 +603,7 @@
    "outputs": [],
    "source": [
     "lowsnr_path = \"./../data/mito-confocal-lowsnr.tif\"\n",
-    "n_test_images = 10\n",
+    "n_test_images = 5\n",
     "# load the data\n",
     "test_set = tifffile.imread(lowsnr_path)\n",
     "test_set = test_set[:n_test_images, np.newaxis]\n",
diff --git a/04_DenoiSplit/exercise.ipynb b/04_DenoiSplit/exercise.ipynb
index 16ec2ae..85eaeda 100644
--- a/04_DenoiSplit/exercise.ipynb
+++ b/04_DenoiSplit/exercise.ipynb
@@ -796,7 +796,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4d103864",
+   "id": "fc2ed8e0",
    "metadata": {},
    "source": [
     "<hr style=\"height:2px;\"><div class=\"alert alert-block alert-success\"><h1>End of the exercise</h1>\n",