fixed minor bugs in 006 and 007 after Jason

Author: giumas

006_Read_and_Write_Text_Files.ipynb

@@ -19,7 +19,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "You have learned about lists and how to write your own functions with loops and conditional statements. This allows you to write programs performing a variety of tasks. \n",
+    "You have learned about lists and how to [write your own functions](005_Write_Your_Own_Functions.ipynb) with [loops](004_Loops.ipynb) and [conditional statements](003_Conditional_Execution.ipynb). This allows you to write programs performing a variety of tasks. \n",
     "\n",
     "However, a convenient mechanism to access data that you want to analyze is currently missing. In this notebook, we will explore the use of [files](https://en.wikipedia.org/wiki/Computer_file) since they are a common way to access stored data."
    ]
@@ -78,7 +78,7 @@
    "source": [
     "<img align=\"left\" width=\"6%\" style=\"padding-right:10px;\" src=\"images/key.png\">\n",
     "\n",
-    "In Python, a **module** is a file containing definitions and statements. "
+    "In Python, a **module** is a file containing code (e.g., definitions and statements). "
    ]
   },
   {
@@ -183,7 +183,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "To be able to access the `data` sub-folder, we extend the previous code using `os.path.join()` and `os.path.exist()` functions to:\n",
+    "To be able to access the `data` sub-folder, we extend the previous code using `os.path.join()` and `os.path.exists()` functions to:\n",
     "\n",
     "- Create the absolute path to the `data` sub-folder.\n",
     "- Check whether the resulting path actually exists."
@@ -242,7 +242,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "We will now retrieve all the paths to the files in the `data` folder. Specifically, we will create a function `get_data_paths()` that returns a list containing all the files in that folder, using the `os.listdir()` function."
+    "We will now retrieve all the paths to the files in the `data` folder. Specifically, we will create a function `get_data_paths()` that returns a list containing all the files in that folder, using the `os.listdir()` function from the `os` module."
    ]
   },
   {
@@ -251,6 +251,8 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "import os\n",
+    "\n",
     "def get_data_paths():\n",
     "    data_paths = list()  # create an empty list to be populated and returned\n",
     "    data_folder = get_data_folder() # call the function you created to return the data directory path\n",
@@ -289,7 +291,7 @@
    "source": [
     "<img align=\"left\" width=\"6%\" style=\"padding-right:10px;\" src=\"images/key.png\">\n",
     "\n",
-    "You do not need to remember all the names of the available Python functions, but you need to learn how to search for them. The [official Python documentation](https://docs.python.org/3.6/index.html) is a good place to start. You can also get a list of the functions in the `os.path` module by entering `dir('os.path')` in a code cell."
+    "You do not need to remember all the names of the available Python functions, but you need to learn how to search for them. The [official Python documentation](https://docs.python.org/3.6/index.html) is a good place to start. You can also get a list of the functions in the `os.path` module by entering `dir(os.path)` in a code cell."
    ]
   },
   {
@@ -428,7 +430,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "You may ask why there are 100 characters instead of 80? Each of the 20 rows has 4 visible characters (e.g., `30.8`), but there is also the invisible [newline character](https://en.wikipedia.org/wiki/Newline) (i.e., `\\n`) that text editors treat as a new line. Thus, `(4+1) * 20 = 100` characters."
+    "You may ask why there are 100 characters instead of 80? Each of the 20 rows has 4 visible characters (e.g., `30.8`), but there is also the invisible [newline character](https://en.wikipedia.org/wiki/Newline) (i.e., `\\n`) that text editors treat as a break between two lines. Thus, `(4+1) * 20 = 100` characters."
    ]
   },
   {

007_Dictionaries_and_Metadata.ipynb

@@ -73,7 +73,7 @@
     "\n",
     "- All the item pairs are printed between curly brackets (i.e., `{`, `}`). \n",
     "- The items are separated by a comma (e.g., the pair `\"Li\": \"Lithium\"` is an item). \n",
-    "- For each item, the two parts are separated by a `-`: the key on the left (e.g., `\"Li\"`) and the value on the right (e.g., `\"Lithium\"`).\n"
+    "- For each item, the two parts are separated by a `:` with the key (e.g., `\"Li\"`) on the left and the value (e.g., `\"Lithium\"`) on the right."
    ]
   },
   {