diff --git a/README.md b/README.md
index 5990e18..e88ed8a 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ This tutorial helps you to learn automated testing in Python 3 using the `pytest
 
 *Captain Ahab was vicious because Moby Dick, the white whale, had bitten off his leg. So the captain set sail for a hunt. For months he was searching the sea for the white whale. The captain finally attacked the whale with a harpoon. Unimpressed, the whale devoured captain, crew and ship. The whale won.*
 
-![tick marks while counting words](../images/counting470.png "Counting words")
+![tick marks while counting words](images/counting470.png "Counting words")
 
 Herman Melville's book *“Moby Dick”* describes the epic fight between the captain of a whaling ship and a whale. In the book, the whale wins by eating most of the other characters. **But does he also win by being mentioned more often?**
 
@@ -19,13 +19,19 @@ Herman Melville's book *“Moby Dick”* describes the epic fight between the ca
 
 clone the repository:
 
-    :::bash
-    git clone https://github.com/krother/python_testing_tutorial.git
+```bash
+git clone https://github.com/krother/python_testing_tutorial.git
+```
 
 install **pytest**:
 
-    :::bash
-    pip install pytest
+```bash
+pip install pytest
+```
+
+## Getting Started
+
+Start with the first exercises in the chapter [Unit Tests](articles/unit_tests.md)!
 
 ## Chapters
 
@@ -65,4 +71,4 @@ Attribution License 4.0.
 
 ## Contributors
 
-Kristian Rother, Magdalena Rother, Daniel Szoska
+Kristian Rother, Magdalena Rother, Daniel Szoska, Malte Bonart
diff --git a/articles/challenges.md b/articles/challenges.md
deleted file mode 100644
index 24a0a40..0000000
--- a/articles/challenges.md
+++ /dev/null
@@ -1,53 +0,0 @@
-
-# Challenges
-
-## 1. Unit Tests
-
-### 1.1 Test a Python function
-The function **main()** in the module **word_counter.py** calculates the number of words in a text body.
-
-For instance, the following sentence contains **three** words:
-
-    Call me Ishmael
-
-Your task is to prove that the **main()** function calculates the number of words in the sentence correctly with **three**.
-
-Use the example test in **test_1_1_unit_test.py**.
-
-### 1.2 Test proves if code is broken
-The test in the module **test_failing_code.py** fails, because there is a bug in the function **word_counter.average_word_length()**. In the sentence
-
-    Call me Ishmael
-
-The words are **four, two,** and **seven** characters long. This gives an average of:
-
-    >>> (4 + 2 + 7) / 3.0
-    4.333333333333333
-
-Your task is to fix the code, so that the test passes.
-
-Use the example in **test_1_2_broken_code.py**.
-
-### 1.3 Code proves if tests are broken
-The test in the module **test_failing_test.py** fails, because there is a bug in the test file.
-
-Your task is to fix the test, so that the test passes. Use the example in **test_1_3_broken_test.py**.
-
-
-### 1.4 Test border cases
-High quality tests cover many different situations. The most common situations for the program **word_counter.py** include:
-
-| test case | description | example input | expected output
-|-----------|-------------|---------------|-----------------
-| empty | input is valid, but empty | "" | 0
-| minimal | smallest reasonable input | "whale" | 1
-| typical | representative input | "whale eats captain" | 3
-| invalid | input is supposed to fail | 777 | *Exception raised*
-| maximum | largest reasonable input | *Melville's entire book* | *more than 200000*
-| sanity | program recycles its own output | *TextBody A created from another TextBody B* | *A equals B*
-| nasty | difficult example | "That #~&%* program still doesn't work!" | 6
-
-Your task is to make all tests in **test_1_4_border_cases.py** pass.
-
-
-----
diff --git a/articles/fixtures.md b/articles/fixtures.md
index 8b51b35..cd4441c 100644
--- a/articles/fixtures.md
+++ b/articles/fixtures.md
@@ -13,12 +13,13 @@ There, add a function that loads the file `data/mobydick_summary.txt`:
 
 Place the decorator `@pytest.fixture` on top of it:
 
-    :::python3
-    import pytest
+```python
+import pytest
 
-    @pytest.fixture
-    def text_summary():
-        return open(...).read()
+@pytest.fixture
+def text_summary():
+    return open(...).read()
+```
 
 ----
 
@@ -26,9 +27,10 @@ Place the decorator `@pytest.fixture` on top of it:
 
 Now create a module `test_corpus.py` with a function that uses the fixture:
 
-    :::python3
-    def test_short_sample(text_summary):
-        assert count_words(text_summary) == 77
+```python
+def test_short_sample(text_summary):
+    assert count_words(text_summary) == 77
+```
 
 Execute the module with `pytest`. Note that you **do not** need to import `conftest`. Pytest does that automatically.
 
@@ -44,11 +46,12 @@ Create a fixture for the full text of the book `mobydick_full.txt` as well.
 
 Create a fixture in `conftest.py` that prepares a dictionary with word counts using the `word_counter.count_words_dict()` function.
 
-    :::python3
-    from word_counter import count_words_dict
+```python
+from word_counter import count_words_dict
 
-    @pytest.fixture
-    def count_dict(text_summary):
-    	return ...
+@pytest.fixture
+def count_dict(text_summary):
+    return ...
+```
 
 Write a simple test that makes sure the dictionary is not empty.
diff --git a/articles/mock_objects.md b/articles/mock_objects.md
deleted file mode 100644
index 428b9b2..0000000
--- a/articles/mock_objects.md
+++ /dev/null
@@ -1,8 +0,0 @@
-
-# Mock Objects
-
-### Exercise 1: Using a Mock Object
-
-The function **word_report.get_top_words()** requires an instance of the class **TextBody**. You need to test the function, excluding the possibility that the **TextBody** class is buggy. To do so, you need to replace the class by a **Mock Object**, a simple placeholder.
-
-Your task is to write a test for the function **word_counter.get_top_words()** that does not use the class **TextBody**.
diff --git a/articles/multiple_packages.md b/articles/multiple_packages.md
deleted file mode 100644
index 479ea20..0000000
--- a/articles/multiple_packages.md
+++ /dev/null
@@ -1,20 +0,0 @@
-### Exercise 5: Import test data in multiple test packages
-In a big software project, your tests are distributed to two packages. Both **test_first.py** and **test_second.py** require the variable **MOBYDICK_SUMMARY** from the module **test data.py**. The package structure is like this:
-
-    testss/
-        test_a/
-            __init__.py
-            test_first.py
-        test_b/
-            __init__.py
-            test_second.py
-        __init__.py
-        test_data.py
-        test_all.py
-
-Your task is to make sure that the variable **MOBYDICK_SUMMARY** is correctly imported to both test modules, so that the tests pass for all of:
-
-    tests/test_a/test_first.py
-    tests/test_b/test_second.py
-    tests/test_all.py
-
diff --git a/articles/organizing_tests.md b/articles/organizing_tests.md
index fd79c5b..7f3402b 100644
--- a/articles/organizing_tests.md
+++ b/articles/organizing_tests.md
@@ -9,11 +9,12 @@ Make sure the name of the class starts with the word `Test`.
 Indent your test functions so that they belong to the class.
 Add `self` as the first parameter of each function:
 
-    :::python3
-    class TestDummy:
+```python
+class TestDummy:
 
-        def test_dummy(self):
-            assert ...
+    def test_dummy(self):
+        assert ...
+```
 
 ----
 
@@ -21,8 +22,9 @@ Add `self` as the first parameter of each function:
 
 Run all tests written so far by simply typing
 
-    :::bash
-    pytest
+```bash
+python -m pytest
+```
 
 ----
 
@@ -30,18 +32,21 @@ Run all tests written so far by simply typing
 
 Run only one test file:
 
-    :::bash
-    pytest FILE_NAME
+```bash
+python -m pytest FILE_NAME
+```
 
 Run only one test class:
 
-    :::bash
-    pytest FILE_NAME::CLASS_NAME
+```bash
+pytest -m pytest FILE_NAME::CLASS_NAME
+```
 
 Finally, run a single test:
 
-    :::bash
-    pytest FILE_NAME::CLASS_NAME::TEST_NAME
+```bash
+pytest -m pytest FILE_NAME::CLASS_NAME::TEST_NAME
+```
 
 ----
 
@@ -51,7 +56,8 @@ Find out which options of pytest do the following:
 
 *more verbose output | re-run failing tests | stop on first test that fails*
 
-    :::bash
-    pytest -lf
-    pytest -v
-    pytest -x
+```bash
+pytest --lf
+pytest -v
+pytest -x
+```
diff --git a/articles/parameterized.md b/articles/parameterized.md
index 72077fd..e0397cf 100644
--- a/articles/parameterized.md
+++ b/articles/parameterized.md
@@ -5,15 +5,16 @@
 
 The tests in `test_parameterized.py` check a list of pairs (word, count) that apply to the text file `mobydick_summary.txt`:
 
-    :::python3
-    PAIRS = [
-        ('whale', 5),
-        ('goldfish', 0),
-        ('captain', 4),
-        ('white', 2),
-        ('jellyfish', 99),
-       ('harpoon', 1),
-    ]
+```python
+PAIRS = [
+    ('whale', 5),
+    ('goldfish', 0),
+    ('captain', 4),
+    ('white', 2),
+    ('jellyfish', 99),
+    ('harpoon', 1),
+]
+```
 
 Run the tests and see what happens.
 
@@ -34,12 +35,13 @@ We will create six tests from the example data.
 Use the **test parametrization in pytest**.
 Change the test function by adding the following decorator:
 
-    :::python3
-    import pytest
+```python
+import pytest
 
-    @pytest.mark.parametrize('word, number', PAIRS)
-    def test_count_words_dict(word, number):
-        ...
+@pytest.mark.parametrize('word, number', PAIRS)
+def test_count_words_dict(word, number):
+    ...
+```
 
 The two arguments will be filled in automatically.
 Now remove the `for` loop.
diff --git a/articles/test_coverage.md b/articles/test_coverage.md
index 0fc6f34..8016558 100644
--- a/articles/test_coverage.md
+++ b/articles/test_coverage.md
@@ -3,8 +3,9 @@
 
 For the next exercises, you need to install a small plugin:
 
-    :::bash
-    pip install pytest-cov
+```bash
+pip install pytest-cov
+```
 
 ----
 
@@ -12,8 +13,9 @@ For the next exercises, you need to install a small plugin:
 
 Calculate the percentage of code covered by automatic tests:
 
-    :::bash
-    pytest --cov=.
+```bash
+python -m pytest --cov=.
+```
 
 Instead of the `.` you can insert the path you would like to see in the coverage report.
 
@@ -24,8 +26,9 @@ Check whether any hidden files have appeared.
 ### Exercise 2: Identify uncovered lines
 Find out which lines are not covered by tests. Execute
 
-    :::bash
-    coverage html
+```bash
+python -m pytest --cov=. --cov-report term-missing
+```
 
 Open the resulting file `htmlcov/index.html` in a web browser.
 
diff --git a/articles/unit_tests.md b/articles/unit_tests.md
index 1fcf1f7..d2d9797 100644
--- a/articles/unit_tests.md
+++ b/articles/unit_tests.md
@@ -5,17 +5,19 @@
 
 #### How many words are in the following sentence?
 
-    :::bash
-    Call me Ishmael.
+```bash
+Call me Ishmael.
+```
 
 ----
 
 #### How many words are in the next sentence?
 
-    :::bash
-    "you haint no objections to sharing a harpooneer's blanket,
-    have ye? I s'pose you are goin' a-whalin',
-    so you'd better get used to that sort of thing."
+```bash
+"you haint no objections to sharing a harpooneer's blanket,
+have ye? I s'pose you are goin' a-whalin',
+so you'd better get used to that sort of thing."
+```
 
 
 ----
@@ -26,15 +28,17 @@ The function `count_words()` in the module **word_counter.py** calculates the nu
 
 For instance, we would expect the following input to result in a word count of `3`:
 
-    :::bash
-    Call me Ishmael
+```bash
+Call me Ishmael
+```
 
 Your task is to prove that the `count_words()` function in fact returns `3`.
 
 Run the example test in `test_unit_test.py` with
 
-    :::bash
-    pytest test_unit_test.py
+```bash
+python -m pytest test/test_unit_test.py
+```
 
 ----
 
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diff --git a/cover.jpg b/images/cover.jpg
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diff --git a/mobydick/word_counter.py b/mobydick/word_counter.py
new file mode 100644
index 0000000..7621529
--- /dev/null
+++ b/mobydick/word_counter.py
@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+"""
+Code that is being tested
+"""
+
+def split_to_words(text):
+    '''split a string into tokens'''
+    if type(text) != str:
+        raise TypeError('accepts only string input.')
+    words = text.split(' ')
+    return words
+
+def count_words(text):
+    '''count number of words in a text'''
+    words = split_to_words(text)
+    return len(words)
+
+def count_word(text, word):
+    '''count the frequency of a word in a text'''
+    words = split_to_words(text)
+    return words.count(word)
+
+def count_words_dict(text):
+    '''Returns a dictionary of word counts'''
+    words = split_to_words(text)
+    d = {}
+
+    for word in words:
+        d.setdefault(word, 0)
+        d[word] += 1
+
+    return d
diff --git a/test/test_broken.py b/test/test_broken.py
index e16013b..7a53c7b 100644
--- a/test/test_broken.py
+++ b/test/test_broken.py
@@ -9,7 +9,7 @@
 Find out which is which and fix both.
 """
 
-from word_counter import count_words
+from mobydick.word_counter import count_words
 
 
 def test_count_words_tabs():
diff --git a/test/test_parameterized.py b/test/test_parameterized.py
index f65cd88..e925eac 100644
--- a/test/test_parameterized.py
+++ b/test/test_parameterized.py
@@ -1,7 +1,6 @@
+from mobydick.word_counter import count_words_dict
 
-from word_counter import count_words_dict
-
-MOBYDICK_SUMMARY = open('../data/mobydick_summary.txt').read()
+MOBYDICK_SUMMARY = open('./data/mobydick_summary.txt').read()
 
 
 PAIRS = [
@@ -15,6 +14,6 @@
 
 
 def test_count_words_dict():
-    counts = count_words_dict(text)
+    counts = count_words_dict(MOBYDICK_SUMMARY)
     for word, number in PAIRS:
         assert counts[word] == number
diff --git a/test/test_unit_test.py b/test/test_unit_test.py
index 4cad767..b7638c4 100644
--- a/test/test_unit_test.py
+++ b/test/test_unit_test.py
@@ -2,9 +2,10 @@
 Example of a Unit Test
 """
 
-from word_counter import count_words
+from mobydick.word_counter import count_words
+
 
 def test_count_words():
     """Count words in a short sentence"""
-    n = count_words("Call me Ishmael")
-    assert n == 3
+    text = "Call me Ishmael"
+    assert count_words(text) == 3
diff --git a/test/word_counter.py b/test/word_counter.py
deleted file mode 100644
index af7a7d7..0000000
--- a/test/word_counter.py
+++ /dev/null
@@ -1,16 +0,0 @@
-"""
-Code that is being tested
-"""
-
-def count_words(text):
-    if type(text) != str:
-        raise TypeError('word counter accepts only string input.')
-    words = text.split(' ')
-    return len(words)
-
-
-def count_words_dict(text, n):
-    '''Returns the n most frequent words.'''
-    d = {'dummy': 1}
-    ...
-    return d