Updated more language

index.ipynb

@@ -30,7 +30,7 @@
     "\n",
     "### Data in Memory\n",
     "\n",
-    "In the previous lessons, we have mainly emphasized working with Python variables *in memory*. When something is in memory, that means that it can be easily modified and that it no longer exists once the software using it (in this case, a Python kernel) stops running.\n",
+    "When something is in memory, that means that it can be easily modified and that it no longer exists once the software using it (in this case, a Python kernel) stops running.\n",
     "\n",
     "For example, take this code snippet:"
    ]
@@ -180,7 +180,7 @@
     "\n",
     "In contrast to data in memory, files *on disk* are stored more permanently.\n",
     "\n",
-    "As we have seen previously, we can view a list of files in the current directory using the bash command `ls`:"
+    "We can view a list of files in the current directory using the bash command `ls`:"
    ]
   },
   {