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@@ -326,6 +326,15 @@ Oops!  That's not what you wanted. Fix it so that the `symbols` variable holds t
 >>>
 ```
 
+Add `'HPQ'` to the front the string:
+
+```python
+>>> symbols = ?
+>>> symbols
+'HPQ,AAPL,IBM,MSFT,YHOO,SCO,GOOG'
+>>>
+```
+
 In these examples, it might look like the original string is being
 modified, in an apparent violation of strings being read only.  Not
 so. Operations on strings create an entirely new string each
 
@@ -1,8 +1,12 @@
+[Contents](../Contents) \| [Previous (1.4 Strings)](04_Strings) \| [Next (1.6 Files)](06_Files)
+
 # 1.5 Lists
 
+This section introduces lists, Python's primary type for holding an ordered collection of values.
+
 ### Creating a List
 
-Use square brackets to define a list:
+Use square brackets to define a list literal:
 
 ```python
 names = [ 'Elwood', 'Jake', 'Curtis' ]
@@ -12,7 +16,7 @@ nums = [ 39, 38, 42, 65, 111]
 Sometimes lists are created by other methods.  For example, a string can be split into a
 list using the `split()` method:
 
-```pycon
+```python
 >>> line = 'GOOG,100,490.10'
 >>> row = line.split(',')
 >>> row
@@ -53,7 +57,7 @@ Negative indices count from the end.
 names[-1] # 'Curtis'
 ```
 
-You can change any item in the list.
+You can change any item in a list.
 
 ```python
 names[1] = 'Joliet Jake'
@@ -83,7 +87,7 @@ s * 3   # [1, 2, 3, 1, 2, 3, 1, 2, 3]
 
 ### List Iteration and Search
 
-Iterating over the list contents.
+Use `for` to iterate over the list contents.
 
 ```python
 for name in names:
@@ -117,8 +121,9 @@ names.remove('Curtis')
 del names[1]
 ```
 
-Removing an item does not create a hole.  Other items will move down to fill the space vacated.
-If there are more than one occurrence of the element, `.remove()` will remove only the first occurrence.
+Removing an item does not create a hole.  Other items will move down
+to fill the space vacated.  If there are more than one occurrence of
+the element, `remove()` will remove only the first occurrence.
 
 ### List Sorting
 
@@ -137,33 +142,39 @@ s = ['foo', 'bar', 'spam']
 s.sort()                    # ['bar', 'foo', 'spam']
 ```
 
+Use `sorted()` if you'd like to make a new list instead:
+
+```python
+t = sorted(s)               # s unchanged, t holds sorted values
+```
+
 ### Lists and Math
 
 *Caution: Lists were not designed for math operations.*
 
-```pycon
+```python
 >>> nums = [1, 2, 3, 4, 5]
 >>> nums * 2
 [1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
 >>> nums + [10, 11, 12, 13, 14]
 [1, 2, 3, 4, 5, 10, 11, 12, 13, 14] >>>
 ```
 
-Specifically, lists don't represent vectors/matrices as in MATLAB, Octave, IDL, etc.
+Specifically, lists don't represent vectors/matrices as in MATLAB, Octave, R, etc.
 However, there are some packages to help you with that (e.g. [numpy](https://numpy.org)).
 
 ## Exercises
 
 In this exercise, we experiment with Python's list datatype. In the last section,
 you worked with strings containing stock symbols.
 
-```pycon
+```python
 >>> symbols = 'HPQ,AAPL,IBM,MSFT,YHOO,DOA,GOOG'
 ```
 
 Split it into a list of names using the `split()` operation of strings:
 
-```pycon
+```python
 >>> symlist = symbols.split(',')
 ```
 
@@ -228,7 +239,7 @@ For instance, in the above example, the last two items of `symlist` got replaced
 The `for` loop works by looping over data in a sequence such as a list.
 Check this out by typing the following loop and watching what happens:
 
-```pycon
+```python
 >>> for s in symlist:
         print('s =', s)
 # Look at the output
@@ -238,7 +249,7 @@ Check this out by typing the following loop and watching what happens:
 
 Use the `in` or `not in` operator to check if `'AIG'`,`'AA'`, and `'CAT'` are in the list of symbols.
 
-```pycon
+```python
 >>> # Is 'AIG' IN the `symlist`?
 True
 >>> # Is 'AA' IN the `symlist`?
@@ -252,7 +263,7 @@ True
 
 Use the `append()` method to add the symbol `'RHT'` to end of `symlist`.
 
-```pycon
+```python
 >>> # append 'RHT'
 >>> symlist
 ['HPQ', 'AAPL', 'AIG', 'MSFT', 'YHOO', 'GOOG', 'RHT']
@@ -261,7 +272,7 @@ Use the `append()` method to add the symbol `'RHT'` to end of `symlist`.
 
 Use the `insert()` method to insert the symbol `'AA'` as the second item in the list.
 
-```pycon
+```python
 >>> # Insert 'AA' as the second item in the list
 >>> symlist
 ['HPQ', 'AA', 'AAPL', 'AIG', 'MSFT', 'YHOO', 'GOOG', 'RHT']
@@ -270,7 +281,7 @@ Use the `insert()` method to insert the symbol `'AA'` as the second item in the
 
 Use the `remove()` method to remove `'MSFT'` from the list.
 
-```pycon
+```python
 >>> # Remove 'MSFT'
 >>> symlist
 ['HPQ', 'AA', 'AAPL', 'AIG', 'YHOO', 'GOOG', 'RHT']
@@ -281,7 +292,7 @@ Append a duplicate entry for `'YHOO'` at the end of the list.
 
 *Note: it is perfectly fine for a list to have duplicate values.*
 
-```pycon
+```python
 >>> # Append 'YHOO'
 >>> symlist
 ['HPQ', 'AA', 'AAPL', 'AIG', 'YHOO', 'GOOG', 'RHT', 'YHOO']
@@ -290,7 +301,7 @@ Append a duplicate entry for `'YHOO'` at the end of the list.
 
 Use the `index()` method to find the first position of `'YHOO'` in the list.
 
-```pycon
+```python
 >>> # Find the first index of 'YHOO'
 4
 >>> symlist[4]
@@ -300,15 +311,15 @@ Use the `index()` method to find the first position of `'YHOO'` in the list.
 
 Count how many times `'YHOO'` is in the list:
 
-```pycon
+```python
 >>> symlist.count('YHOO')
 2
 >>>
 ```
 
 Remove the first occurrence of `'YHOO'`.
 
-```pycon
+```python
 >>> # Remove first occurrence 'YHOO'
 >>> symlist
 ['HPQ', 'AA', 'AAPL', 'AIG', 'GOOG', 'RHT', 'YHOO']
@@ -322,7 +333,7 @@ However, we'll see an elegant way to do this in section 2.
 
 Want to sort a list?  Use the `sort()` method. Try it out:
 
-```pycon
+```python
 >>> symlist.sort()
 >>> symlist
 ['AA', 'AAPL', 'AIG', 'GOOG', 'HPQ', 'RHT', 'YHOO']
@@ -331,7 +342,7 @@ Want to sort a list?  Use the `sort()` method. Try it out:
 
 Want to sort in reverse? Try this:
 
-```pycon
+```python
 >>> symlist.sort(reverse=True)
 >>> symlist
 ['YHOO', 'RHT', 'HPQ', 'GOOG', 'AIG', 'AAPL', 'AA']
@@ -345,7 +356,7 @@ Note: Sorting a list modifies its contents 'in-place'.  That is, the elements of
 Want to take a list of strings and join them together into one string?
 Use the `join()` method of strings like this (note: this looks funny at first).
 
-```pycon
+```python
 >>> a = ','.join(symlist)
 >>> a
 'YHOO,RHT,HPQ,GOOG,AIG,AAPL,AA'
@@ -363,7 +374,7 @@ Use the `join()` method of strings like this (note: this looks funny at first).
 Lists can contain any kind of object, including other lists (e.g., nested lists).
 Try this out:
 
-```pycon
+```python
 >>> nums = [101, 102, 103]
 >>> items = ['spam', symlist, nums]
 >>> items
@@ -375,7 +386,7 @@ The first element is a string, but the other two elements are lists.
 
 You can access items in the nested lists by using multiple indexing operations.
 
-```pycon
+```python
 >>> items[0]
 'spam'
 >>> items[0][0]