Hints

General

The Python Docs Tutorial for strings has an overview of the Python str type.
String methods .join() and .split() ar very helpful when processing strings.
The Python Docs on Sequence Types has a rundown of operations common to all sequences, including strings, lists, tuples, and ranges.

There's four activities in the assignment, each with a set of text or words to work with.

1. Add a prefix to a word

Small strings can be concatenated with the + operator.

2. Add prefixes to word groups

Believe it or not, <str>.join() is all you need.
Like <str>.split(), <str>.join() can take an arbitrary-length string, made up of any unicode code points.

3. Remove a suffix from a word

Strings can be both indexed and sliced from either the left (starting at 0) or the right (starting at -1).
If you want the last code point of an arbitrary-length string, you can use [-1].
The last three letters in a string can be "sliced off" using a negative index. e.g. 'beautiful'[:-3] == 'beauti'

4. Extract and transform a word

Using <str>.split() returns a list of strings broken on white space.
lists are sequences, and can be indexed.
<str>.split() can be direcly indexed. e.g. 'Exercism rocks!'.split()[0] == 'Exercism'
Be careful of punctuation! Periods can be removed via slice: 'dark.'[:-1] == 'dark'