diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..4342f4c
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,17 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "ET: Debug Python (unittest)",
+      "type": "debugpy",
+      "request": "launch",
+      "program": "-m",
+      "args": ["unittest", "${file}"],
+      "console": "integratedTerminal",
+      "justMyCode": true
+    }
+  ]
+}
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 5a90e20..5f1bbc6 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -113,5 +113,8 @@
   },
 
   // Enable/disable update table of contents on save
-  "markdown.extension.toc.updateOnSave": false
+  "markdown.extension.toc.updateOnSave": false,
+  "python.testing.unittestArgs": ["-v", "-s", ".", "-p", "test_*.py"],
+  "python.testing.pytestEnabled": false,
+  "python.testing.unittestEnabled": true
 }
diff --git a/2_predictive_stepping/lesson_plan.md b/2_predictive_stepping/lesson_plan.md
index 9bbef14..dcc5ce8 100644
--- a/2_predictive_stepping/lesson_plan.md
+++ b/2_predictive_stepping/lesson_plan.md
@@ -167,9 +167,18 @@ _(live demo)_
 
 class: middle, center
 
-## Predictive Stepping
+## Predictive Stepping:  _demo_
 
-### _demo_
+Before stepping:
+
+- Which line will execute next?
+- What will happen?
+- What will will change in memory?
+
+After stepping:
+
+- Were your predictions correct?
+- if not, what did you not understand?
 
 ---
 
diff --git a/3_documenting_and_testing/README.md b/3_documenting_and_testing/README.md
index 14e1954..bf8587e 100644
--- a/3_documenting_and_testing/README.md
+++ b/3_documenting_and_testing/README.md
@@ -70,9 +70,12 @@ master all of the skills introduced in this workshop.
 
 ### Function Testing
 
-- 🥚 You can use a sandbox file to informally explore a function's _behavior_.
 - 🥚 You can read and run unit tests to understand a function's _behavior_.
-- 🥚 You can import a module in your console and run its doctest.
-- 🥚 You can write a simple suite of unit tests with some boundary cases.
+- 🥚 You can step through test cases in a debugger to understand a function's _strategy & implementation_.
+  - open the function and tests side-by-side
+  - place a breakpoint on the first line of the function
+  - open the VSCode debugger pane
+  - launch the `ET: Debug Python (unittest)` process
+- 🥚 You can write a suite of unit tests with some boundary cases.
 - 🐣 You can write a full suite of unit tests including comprehensive boundary
-  cases, assertions checks, and glass box tests.
+  cases and assertions checks.
diff --git a/3_documenting_and_testing/examples/fibonacci_list.py b/3_documenting_and_testing/examples/fibonacci_list.py
index 5dc3523..050a9c1 100644
--- a/3_documenting_and_testing/examples/fibonacci_list.py
+++ b/3_documenting_and_testing/examples/fibonacci_list.py
@@ -61,6 +61,7 @@ def fibonacci_list(sequence_length: int) -> list[int]:
 
     # sum the previous two values and append them to the list
     sequence = [0, 1]
-    for _ in range(2, sequence_length):
+    while len(sequence) < sequence_length:
         sequence.append(sequence[-1] + sequence[-2])
+
     return sequence
diff --git a/3_documenting_and_testing/examples/tests/test_fibonacci_list.py b/3_documenting_and_testing/examples/tests/test_fibonacci_list.py
index a20d909..3a0d0bb 100644
--- a/3_documenting_and_testing/examples/tests/test_fibonacci_list.py
+++ b/3_documenting_and_testing/examples/tests/test_fibonacci_list.py
@@ -24,19 +24,25 @@ class TestFibLib(unittest.TestCase):
 
     def test_0(self):
         """It should evaluate 0 to []"""
-        self.assertEqual(fibonacci_list(0), [])
+        actual = fibonacci_list(0) # call function with test arguments
+        expected = [] # hand-write the expected return value
+        self.assertEqual(actual, expected)
 
     def test_1(self):
         """It should evaluate 1 to [0]"""
-        self.assertEqual(fibonacci_list(1), [0])
+        actual = fibonacci_list(1)
+        expected = [0]
+        self.assertEqual(actual, expected)
 
     def test_2(self):
         """It should evaluate 2 to [0, 1]"""
-        self.assertEqual(fibonacci_list(2), [0, 1])
+        actual = fibonacci_list(2)
+        self.assertEqual(actual, [0, 1])
 
     def test_3(self):
         """It should evaluate 3 to [0, 1, 1]"""
-        self.assertEqual(fibonacci_list(3), [0, 1, 1])
+        expected = [0, 1, 1]
+        self.assertEqual(fibonacci_list(3), expected)
 
     def test_4(self):
         """It should evaluate 4 to [0, 1, 1, 2]"""
diff --git a/3_documenting_and_testing/exercises/mystery_1.py b/3_documenting_and_testing/exercises/mystery_1.py
index 4db5d42..d04fa14 100644
--- a/3_documenting_and_testing/exercises/mystery_1.py
+++ b/3_documenting_and_testing/exercises/mystery_1.py
@@ -1,7 +1,2 @@
-def mystery_1(a):
-    b = len(a)
-    for c in range(b):
-        for d in range(0, b - c - 1):
-            if a[d] > a[d + 1]:
-                a[d], a[d + 1] = a[d + 1], a[d]
-    return a
+def mystery_1(a,b):
+    return a + b
diff --git a/3_documenting_and_testing/exercises/mystery_2.py b/3_documenting_and_testing/exercises/mystery_2.py
index b119701..460dd64 100644
--- a/3_documenting_and_testing/exercises/mystery_2.py
+++ b/3_documenting_and_testing/exercises/mystery_2.py
@@ -1,7 +1,5 @@
-def mystery_2(a, b):
-    c = []
-    while a:
-        if b in a[0]:
-            c.append(a[0])
-        a = a[1:]
-    return c
+def mystery_2(a):
+    if len(a) == 0:
+        return None
+
+    return len(a)
diff --git a/3_documenting_and_testing/exercises/mystery_3.py b/3_documenting_and_testing/exercises/mystery_3.py
index c2b6c43..3e523f9 100644
--- a/3_documenting_and_testing/exercises/mystery_3.py
+++ b/3_documenting_and_testing/exercises/mystery_3.py
@@ -1,8 +1,7 @@
-def mystery_3(a, b=None):
-    if b is None:
-        b = []
-    while a:
-        c = min(a)
-        a.remove(c)
-        b.append(c)
-    return b
+def mystery_3(a, b):
+    if a < b:
+        return a
+    elif a > b:
+        return b
+    else:
+        return a + b
diff --git a/3_documenting_and_testing/exercises/mystery_4.py b/3_documenting_and_testing/exercises/mystery_4.py
index 3e34b73..573fcf1 100644
--- a/3_documenting_and_testing/exercises/mystery_4.py
+++ b/3_documenting_and_testing/exercises/mystery_4.py
@@ -1,6 +1,9 @@
-def mystery_4(a, b):
-    c = []
-    for d in a:
-        if b in d:
-            c.append(d)
-    return c
+def mystery_4(a):
+    b = []
+
+    c = 0
+    while len(b) < a:
+        b.append(c)
+        c = c + 1
+
+    return b
diff --git a/3_documenting_and_testing/exercises/mystery_5.py b/3_documenting_and_testing/exercises/mystery_5.py
new file mode 100644
index 0000000..58badfe
--- /dev/null
+++ b/3_documenting_and_testing/exercises/mystery_5.py
@@ -0,0 +1,8 @@
+def mystery_5(a, b=None):
+    if b is None:
+        b = []
+    while a:
+        c = min(a)
+        a.remove(c)
+        b.append(c)
+    return b
diff --git a/3_documenting_and_testing/exercises/mystery_6.py b/3_documenting_and_testing/exercises/mystery_6.py
new file mode 100644
index 0000000..0b57af7
--- /dev/null
+++ b/3_documenting_and_testing/exercises/mystery_6.py
@@ -0,0 +1,10 @@
+def mystery_6(a, b):
+    if a == 0:
+        return []
+
+    c = []
+    while len(c) < a:
+        c.append(b)
+        b = b + 1
+
+    return c
diff --git a/3_documenting_and_testing/exercises/mystery_7.py b/3_documenting_and_testing/exercises/mystery_7.py
new file mode 100644
index 0000000..ef13d88
--- /dev/null
+++ b/3_documenting_and_testing/exercises/mystery_7.py
@@ -0,0 +1,6 @@
+def mystery_7(a, b):
+    c = []
+    for d in a:
+        if b in d:
+            c.append(d)
+    return c
diff --git a/3_documenting_and_testing/exercises/mystery_8.py b/3_documenting_and_testing/exercises/mystery_8.py
new file mode 100644
index 0000000..aff58ac
--- /dev/null
+++ b/3_documenting_and_testing/exercises/mystery_8.py
@@ -0,0 +1,7 @@
+def mystery_8(a, b):
+    c = []
+    while a:
+        if b in a[0]:
+            c.append(a[0])
+        a = a[1:]
+    return c
diff --git a/3_documenting_and_testing/exercises/mystery_9.py b/3_documenting_and_testing/exercises/mystery_9.py
new file mode 100644
index 0000000..9334577
--- /dev/null
+++ b/3_documenting_and_testing/exercises/mystery_9.py
@@ -0,0 +1,7 @@
+def mystery_9(a):
+    b = len(a)
+    for c in range(b):
+        for d in range(0, b - c - 1):
+            if a[d] > a[d + 1]:
+                a[d], a[d + 1] = a[d + 1], a[d]
+    return a
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_1.py b/3_documenting_and_testing/exercises/tests/test_mystery_1.py
index d65c16c..7a5116a 100644
--- a/3_documenting_and_testing/exercises/tests/test_mystery_1.py
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_1.py
@@ -1,5 +1,6 @@
 import unittest
 
+from ..mystery_1 import mystery_1
 
 class TestMystery1(unittest.TestCase):
     """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_2.py b/3_documenting_and_testing/exercises/tests/test_mystery_2.py
index fdc8ed9..e7a83d6 100644
--- a/3_documenting_and_testing/exercises/tests/test_mystery_2.py
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_2.py
@@ -1,5 +1,6 @@
 import unittest
 
+from ..mystery_2 import mystery_2
 
 class TestMystery2(unittest.TestCase):
     """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_3.py b/3_documenting_and_testing/exercises/tests/test_mystery_3.py
index 60cbbf8..ad283dd 100644
--- a/3_documenting_and_testing/exercises/tests/test_mystery_3.py
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_3.py
@@ -1,5 +1,6 @@
 import unittest
 
+from ..mystery_3 import mystery_3
 
 class TestMystery3(unittest.TestCase):
     """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_4.py b/3_documenting_and_testing/exercises/tests/test_mystery_4.py
index b39536d..80b5426 100644
--- a/3_documenting_and_testing/exercises/tests/test_mystery_4.py
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_4.py
@@ -1,5 +1,6 @@
 import unittest
 
+from ..mystery_4 import mystery_4
 
 class TestMystery4(unittest.TestCase):
     """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_5.py b/3_documenting_and_testing/exercises/tests/test_mystery_5.py
new file mode 100644
index 0000000..5251f12
--- /dev/null
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_5.py
@@ -0,0 +1,6 @@
+import unittest
+
+from ..mystery_5 import mystery_5
+
+class TestMystery5(unittest.TestCase):
+    """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_6.py b/3_documenting_and_testing/exercises/tests/test_mystery_6.py
new file mode 100644
index 0000000..315bee1
--- /dev/null
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_6.py
@@ -0,0 +1,6 @@
+import unittest
+
+from ..mystery_6 import mystery_6
+
+class TestMystery6(unittest.TestCase):
+    """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_7.py b/3_documenting_and_testing/exercises/tests/test_mystery_7.py
new file mode 100644
index 0000000..f8307bf
--- /dev/null
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_7.py
@@ -0,0 +1,6 @@
+import unittest
+
+from ..mystery_7 import mystery_7
+
+class TestMystery7(unittest.TestCase):
+    """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_8.py b/3_documenting_and_testing/exercises/tests/test_mystery_8.py
new file mode 100644
index 0000000..21e8d28
--- /dev/null
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_8.py
@@ -0,0 +1,6 @@
+import unittest
+
+from ..mystery_8 import mystery_8
+
+class TestMystery8(unittest.TestCase):
+    """ """
diff --git a/3_documenting_and_testing/exercises/tests/test_mystery_9.py b/3_documenting_and_testing/exercises/tests/test_mystery_9.py
new file mode 100644
index 0000000..b417d05
--- /dev/null
+++ b/3_documenting_and_testing/exercises/tests/test_mystery_9.py
@@ -0,0 +1,6 @@
+import unittest
+
+from ..mystery_9 import mystery_9
+
+class TestMystery9(unittest.TestCase):
+    """ """
diff --git a/3_documenting_and_testing/lesson_plan.md b/3_documenting_and_testing/lesson_plan.md
index c3587e0..e111512 100644
--- a/3_documenting_and_testing/lesson_plan.md
+++ b/3_documenting_and_testing/lesson_plan.md
@@ -57,7 +57,7 @@ class: middle
 
 class: middle
 
-## Behavior, Strategy, Implementation
+## [Behavior, Strategy, Implementation](./behavior_strategy_implementation.md)
 
 - Naming things!
 
@@ -207,18 +207,28 @@ class: middle
 
 ## Code Review: _demo_
 
-- Open the [code review checklist](./code_review_checklist.md) and work from top to bottom
+- **Open the [code review checklist](./code_review_checklist.md) and work from top to bottom**
 
-- Run tests: `$ python -m unittest path/to/tests/test_file.py`
+_Rely on code quality automations_
 
-- Print the docstring: `$ python -m pydoc path/to/file.py`
+**Print the docstring**: `$ python -m pydoc path/to/file.py`
 
-- Run the doctests: `$ python -m doctest -v path/to/file.py`
-  
-- Check linting:
-  - with VSCode extensions
-  - `$ ruff check ./path/to/file.py`
-  - `$ pylint ./path/to/file.py`
+**Run the doctests**: `$ python -m doctest -v path/to/file.py`
+
+**Run the unit tests**: `$ python -m unittest path/to/tests/test_file.py`
+
+**Step through the tests in the debugger**:  
+
+- open the function and tests side-by-side
+- place a breakpoint in the first line of the function
+- open the VSCode debugger pane
+- start `ET: Debug Python (unittest)`
+
+**Lint the code**:
+
+- _with VSCode extensions_
+- `$ ruff check ./path/to/file.py`
+- `$ pylint ./path/to/file.py`
 
 ---
 
@@ -248,13 +258,7 @@ class: middle, center
 
 class: middle, center
 
-## Learnings + Discussion
-
----
-
-class: middle, center
-
-## Q & A
+## Discussion, Q & A
 
 ---
 
diff --git a/3_documenting_and_testing/prep_work.md b/3_documenting_and_testing/prep_work.md
index 0467757..72b36ca 100644
--- a/3_documenting_and_testing/prep_work.md
+++ b/3_documenting_and_testing/prep_work.md
@@ -1,16 +1,23 @@
 # Prep Work
 
+Familiarize yourself with these resources for understanding and discussing code quality:
+
+- Read through [Behavior, Strategy, Implementation](./behavior_strategy_implementation.md)
+- Read through the [Code Review Checklist](./code_review_checklist.md)
+
+Study and run the [`/examples`](./examples/).  Practice using these _code quality automations_ with `fibonacci_list.py` and `tests/test_fibonacci.py`:
+
+- print the docstring: `$ python -m pydoc path/to/file.py`
+- run the doctests: `$ python -m doctest -v path/to/file.py`
+- run the unit tests: `$ python -m unittest path/to/tests/test_file.py`
+- stepping through unit tests following this process:
+  - open `fibonacci_list.py` and `tests/test_fibonacci.py` side-by-side
+  - place a breakpoint on the first line of the function
+  - open the VSCode debugger pane
+  - launch the `ET: Debug Python (unittest)` process
+
 Familiarize yourself these built-in Python tools for documenting and testing:
 
 - [Docstrings](https://peps.python.org/pep-0257/)
 - [Doctest](https://docs.python.org/3/library/doctest.html)
 - [The `uittest` module](https://docs.python.org/3/library/unittest.html)
-
-Familiarize yourself with these resources for understanding and discussing code quality:
-
-- Read through [Behavior, Strategy, Implementation](./behavior_strategy_implementation.md)
-- Read through the [Code Review Checklist](./code_review_checklist.md)
-- Study and run the [`/examples`](./examples/).  Practice using these commands with `fibonacci_list.py` and `tests/test_fibonacci.py`:
-  - print the docstring: `$ python -m pydoc path/to/file.py`
-  - run the doctests: `$ python -m doctest -v path/to/file.py`
-  - run the tests using `$ python -m unittest path/to/tests/test_file.py`