diff --git a/practice/practice1.py b/practice/practice1.py
index e80efeb..9f38add 100644
--- a/practice/practice1.py
+++ b/practice/practice1.py
@@ -5,7 +5,7 @@ Instructions (READ THIS FIRST!)
 
 Complete the functions in this module according to their docstring.
 
-We have marked each place you need to write code with the word "TODO".
+We have marked each place you need to write code with the word
 As you complete your work in this file, delete each TO-DO comment---this is a
 good habit to get into early! To check your work, you should run this file in
 the Python console and then call each function manually.
diff --git a/practice/prep2.py b/practice/prep2.py
new file mode 100755
index 0000000..07ae930
--- /dev/null
+++ b/practice/prep2.py
@@ -0,0 +1,167 @@
+"""CSC110 Fall 2020 Prep 2: Programming Exercises
+
+Instructions (READ THIS FIRST!)
+===============================
+
+This Python module contains several function headers and descriptions.
+Your task is to complete this module by doing the following for EACH function below:
+
+1. Add a new doctest example to the function description in the space provided.
+   This will ensure you understand what the function is supposed to do.
+2. Write the body of the function so that it does what its description claims.
+
+In some function descriptions, we have written "You may ASSUME..." This means that
+when you are writing each function body, you only have to consider possible values
+for the parameters that satisfy these assumptions.
+
+We have marked each place you need to write a doctest/code with the word 
+As you complete your work in this file, delete each TO-DO comment---this is a
+good habit to get into early! To check your work, you should run this file in
+the Python console and then call each function manually (you can also copy-and-paste)
+with your doctest examples, and possibly other examples.
+
+(We'll cover more techniques for testing your code this week.)
+
+By the way, we *will* be checking that you've added new doctest examples, and that
+your examples correctly illustrate a call to that function. Don't skip this!
+
+Copyright and Usage Information
+===============================
+
+This file is provided solely for the personal and private use of students
+taking CSC110 at the University of Toronto St. George campus. All forms of
+distribution of this code, whether as given or with any changes, are
+expressly prohibited. For more information on copyright for CSC110 materials,
+please consult our Course Syllabus.
+
+This file is Copyright (c) 2020 David Liu and Mario Badr.
+"""
+
+
+def total_slices(num_pizzas: int, slices_per_pizza: int) -> int:
+    """Return the total number of pizza slices in `num_pizzas` pizzas.
+
+    One pizza has `slices_per_pizza` slices.
+
+    You may ASSUME that num_pizzas and slices_per_pizza are both >= 0.
+
+    >>> total_slices(5, 8)  # 5 pizzas with 8 slices per pizza
+    40
+    >>> total_slices(0, 8)  # 0 pizzas with 8 slices per pizza
+    0
+    """
+    assert num_pizzas >= 0 and slices_per_pizza >= 0
+    return num_pizzas * slices_per_pizza
+
+
+def scale_grade(original_grade: float, multiplier: float, bonus: float) -> float:
+    """Return an adjusted grade.
+
+    The original grade is first multiplied by the given multiplier,
+    and then the result is added to the given bonus.
+
+    Grades are capped at 100.0; if the scaling causes the grade to exceed 100.0,
+    100.0 is returned instead.
+
+    You may ASSUME that the original_grade, multiplier, and bonus are all >= 0.
+
+    >>> scale_grade(60.0, 1.2, 10.0)  # 60.0 * 1.2 = 72.0, and 72.0 + 10.0 = 82.0
+    82.0
+    >>> scale_grade(20.0, 4.0, 21.0)  # 20.0 * 4.0 = 80.0, and 80.0 + 21.0 = 110.0 but capped at 100.0
+    100.0
+
+    HINT: one of the max or min functions is useful.
+    """
+    assert original_grade >= 0 and multiplier >= 0 and bonus >= 0
+    return min(100.0, original_grade * multiplier + bonus)
+
+
+def first_characters(strings: set) -> set:
+    """Return a set containing all of the first characters of the given strings.
+
+    You may ASSUME that all of the given strings are non-empty.
+    (An empty string has no first character!)
+
+    >>> letters = first_characters({'David', 'is', 'cool'})
+    >>> letters == {'D', 'i', 'c'}
+    True
+    >>> letters = first_characters(set())
+    >>> letters == set()
+    True
+
+    HINT: use a set comprehension (review Section 1.5 of the Course Notes).
+    You may also need to review Section 1.3 for how to extract a single character
+    from a string.
+    """
+    assert all([len(string) != 0 for string in strings])
+    return {string[0] for string in strings}
+
+
+def scale_grades(original_grades: list, multiplier: float, bonus: float) -> list:
+    """Return a list of adjusted grades.
+
+    original_grades is a list of floats representing the original grades.
+    The multiplier and bonus parameters have the same role as with scale_grade.
+    Each grade is adjusted in the way described in scale_grade above.
+
+    You may ASSUME that the original grades, multiplier, and bonus are all >= 0.
+
+    >>> scale_grades([10.0, 20.2], 1.5, 3.0)
+    [18.0, 33.3]
+    >>> scale_grades([10.0, 20.0, 30.0], 4.0, 21.0)
+    [61.0, 100.0, 100.0]
+    >>> scale_grades([], 0, 0)
+    []
+
+    HINT: use a list comprehension, and call your scale_grade function on each
+    original grade.
+    """
+    assert all([grade >= 0 for grade in original_grades]) and multiplier >= 0 and bonus >= 0
+    return [scale_grade(grade, multiplier, bonus) for grade in original_grades]
+
+
+def word_lengths(text: str) -> dict:
+    """Return a dictionary mapping the words in text to their lengths.
+
+    In the returned dictionary, each key is a word that appears in text,
+    and its corresponding value is its length (number of characters).
+
+    In the given text, words are separated by one or more spaces.
+
+    >>> result = word_lengths('David is   cool')
+    >>> result == {'David': 5, 'is': 2, 'cool': 4}
+    True
+    >>> result = word_lengths('')
+    >>> result == {}
+    True
+    >>> result = word_lengths('    PythonIs   a  snake  中文 ')
+    >>> result == {'PythonIs': 8, 'a': 1, 'snake': 5, '中文': 2}
+    True
+
+    HINT: this is a bit longer than the previous functions. Try the following
+    approach:
+
+        1. Split the given text into words using the str.split method.
+           (Review Section 2.1 if you aren't sure about "methods".)
+           Store the resulting value in a variable.
+        2. Use a dictionary comprehension on the result of Step 1.
+    """
+    words = text.split()
+    return {word: len(word) for word in words}
+
+
+if __name__ == '__main__':
+    # Tester code
+    assert total_slices(5, 8) == 40
+    assert total_slices(0, 8) == 0
+    assert scale_grade(60.0, 1.2, 10.0) == 82.0
+    assert scale_grade(20.0, 4.0, 21.0) == 100.0
+    assert first_characters({'David', 'is', 'cool'}) == {'D', 'i', 'c'}
+    assert first_characters(set()) == set()
+    assert scale_grades([10.0, 20.2], 1.5, 3.0) == [18.0, 33.3]
+    assert scale_grades([10.0, 20.0, 30.0], 4.0, 21.0) == [61.0, 100.0, 100.0]
+    assert scale_grades([], 0, 0) == []
+    assert word_lengths('David is   cool') == {'David': 5, 'is': 2, 'cool': 4}
+    assert word_lengths('') == {}
+    assert word_lengths('    PythonIs   a  snake  中文 ') == {'PythonIs': 8, 'a': 1, 'snake': 5, '中文': 2}
+