diff --git a/lab_04.ipynb b/lab_04.ipynb
index cd1f5b8..a58495a 100644
--- a/lab_04.ipynb
+++ b/lab_04.ipynb
@@ -103,7 +103,9 @@
    "source": [
     "### 0.2 Saving your work\n",
     "\n",
-    "When you finish working on a notebook, save your work using the icon in the menu bar above. Your notebook is stored in the file `lab_04.ipynb` in the lab directory. You can commit your changes to `ipynb` files just like any other file. Once you finish with Jupyter, you can stop the server by pressing **Control + C** in the Terminal. "
+    "When you finish working on a notebook, save your work using the icon in the menu bar above. Your notebook is stored in the file `lab_04.ipynb` in the lab directory. You can commit your changes to `ipynb` files just like any other file. Once you finish with Jupyter, you can stop the server by pressing **Control + C** in the Terminal. \n",
+    "\n",
+    "*If you're doing this lab on a cloud-based platform like Binder, then you can't save your work. So don't close the tab!*"
    ]
   },
   {
@@ -123,7 +125,7 @@
     "\n",
     "### 1.0 Getting started\n",
     "\n",
-    "First, we'll import pandas (using the conventional variable name `pd`) and load the two datasets."
+    "First, we'll import pandas (using the conventional variable name `pd`) and load the two datasets. *Run these cells and every code cell you encounter in this notebook.*"
    ]
   },
   {
@@ -867,7 +869,7 @@
    "id": "b4ad804a-f5f0-441f-bb83-51f360c1c154",
    "metadata": {},
    "source": [
-    "Let's get all the ice pokemon. We can create a boolean series from another series..."
+    "Let's get all the ice pokémon. We can create a boolean series from another series..."
    ]
   },
   {
@@ -1385,7 +1387,7 @@
    "id": "0af5f534-0bec-4577-beee-29b350102265",
    "metadata": {},
    "source": [
-    "Let's get the high-speed ice pokémon. You can join conditions together using the `&` (and) and `|` (or) operators. Due to order of operations, each condition needs to be wrapped in parentheses."
+    "Let's get the high-speed ice pokémon. You can join conditions together using the `&` (and) and `|` (or) operators. `~` means \"not\", so `pokemon[~(pokemon.type == \"Ice\")]` would select all the non-ice pokémon. Due to order of operations, each condition needs to be wrapped in parentheses."
    ]
   },
   {