diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index 3667a53f..3f689e5b 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -13,7 +13,8 @@
 		},
 		"ghcr.io/devcontainers/features/node:1": {},
 		"ghcr.io/devcontainers/features/python:1": {},
-		"ghcr.io/devcontainers-contrib/features/ts-node:1": {}
+		"ghcr.io/devcontainers-contrib/features/ts-node:1": {},
+		"ghcr.io/devcontainers/features/sshd:1": {}
 	},
 	"portsAttributes": {
 	  "80": {
@@ -34,4 +35,4 @@
 			]
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/.github/workflows/check_lesson_08_pr.yml b/.github/workflows/check_lesson_08_pr.yml
new file mode 100644
index 00000000..886e8744
--- /dev/null
+++ b/.github/workflows/check_lesson_08_pr.yml
@@ -0,0 +1,33 @@
+name: Check Lesson 08 Pull Request
+
+on:
+  pull_request:
+    branches: [ "main" ]
+    paths:
+      - "lesson_08/collections/**"
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+
+    # Configure Gradle for optimal use in GiHub Actions, including caching of downloaded dependencies.
+    # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md
+    - name: Setup Gradle
+      uses: gradle/actions/setup-gradle@417ae3ccd767c252f5661f1ace9f835f9654f2b5 # v3.1.0
+
+    - name: Build Lesson 08 with Gradle Wrapper
+      working-directory: ./lesson_08/collections
+      run: ./gradlew check
+
+
diff --git a/.github/workflows/check_push.yml b/.github/workflows/check_push.yml
index d171452e..ee360a01 100644
--- a/.github/workflows/check_push.yml
+++ b/.github/workflows/check_push.yml
@@ -10,6 +10,8 @@ on:
       - "lesson_04/expression/**"
       - "lesson_05/types/**"
       - "lesson_06/conditionals/**"
+      - "lesson_07/objects/**"
+      - "lesson_08/collections/**"
 
 jobs:
   build:
@@ -55,6 +57,10 @@ jobs:
       working-directory: ./lesson_07/objects
       run: ./gradlew assemble && ./gradlew spotlessCheck
 
+    - name: Build Lesson 08 with Gradle Wrapper
+      working-directory: ./lesson_08/collections
+      run: ./gradlew assemble && ./gradlew spotlessCheck
+
     - name: Build Shared Lib with Gradle Wrapper
       working-directory: ./lib/java/codedifferently-instructional
       run: ./gradlew check
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 0be1c0c6..618be647 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,4 +1,9 @@
 {
+    "remote.containers.defaultExtensions": [ "asvetliakov.vscode-neovim"],
+    "remote.extensionKind": {
+        "asvetliakov.vscode-neovim": ["workspace"]
+    },
+    "vscode-neovim.neovimExecutablePaths.linux": "/home/linuxbrew/.linuxbrew/bin/nvim",
     "java.configuration.updateBuildConfiguration": "automatic",
     "java.compile.nullAnalysis.mode": "automatic"
-}
\ No newline at end of file
+}
diff --git a/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/Lesson6.java b/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/Lesson6.java
index 16112932..715b3e99 100644
--- a/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/Lesson6.java
+++ b/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/Lesson6.java
@@ -25,16 +25,16 @@ public static boolean canVote(int age) {
   }
 
   /**
-   * Compares two strings lexographically.
+   * Compares two strings lexicographically.
    *
    * @param value1 The first `String` to compare.
    * @param value2 The second `String` to compare.
-   * @rerturn -1 if a is less than b, 1 if a is greater than b, and 0 otherwise.
+   * @return -1 if a is less than b, 1 if a is greater than b, and 0 otherwise.
    */
   public static int compareStrings(String a, String b) {
-    // The distance will be a number less than 0 if string `a` is lexographically less than `b`, 1
+    // The distance will be a number less than 0 if string `a` is lexicographically less than `b`, 1
     // if it is greater, and 0 if the strings are equal.
-    int distance = Helpers.computeLexographicDistance(a, b);
+    int distance = Helpers.computeLexicographicDistance(a, b);
 
     // TODO(you): Finish this method.
 
@@ -75,10 +75,10 @@ public static double addNumbers(double[] values) {
   }
 
   /**
-   * Returns an array of the first `n` fibonacci numbers starting from 1.
+   * Returns an array of the first `n` Fibonacci numbers starting from 1.
    *
-   * @param n The first `n` of fibonacci values to compute.
-   * @return An array containing the first `n` fibonacci values.
+   * @param n The first `n` of Fibonacci values to compute.
+   * @return An array containing the first `n` Fibonacci values.
    */
   public static int[] getFirstNFibonacciNumbers(int n) {
     return null;
@@ -88,8 +88,8 @@ public static int[] getFirstNFibonacciNumbers(int n) {
    * Finds a value in an array of values.
    *
    * @param values The values to search.
-   * @param The left most index to search.
-   * @param The right most index to search.
+   * @param start The left most index to search.
+   * @param end The right most index to search.
    * @param value The value to look for.
    * @return The index of the value if found in the array and -1 otherwise.
    */
diff --git a/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/util/Helpers.java b/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/util/Helpers.java
index f51626d7..3cc4821b 100644
--- a/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/util/Helpers.java
+++ b/lesson_06/conditionals/conditionals_app/src/main/java/com/codedifferently/lesson6/util/Helpers.java
@@ -2,16 +2,16 @@
 
 public class Helpers {
   /**
-   * Computes a score describing the lexographic distance between two strings. For two strings of
+   * Computes a score describing the lexicographic distance between two strings. For two strings of
    * equal length, the score will be the difference between the first differing character. In the
    * case where either is a sub-string of the other, then the difference in length determines the
    * score.
    *
    * @param a The first string to compare.
    * @param b The second string to compare.
-   * @return A score representing the lexographic distance between two strings.
+   * @return A score representing the lexicographic distance between two strings.
    */
-  public static int computeLexographicDistance(String a, String b) {
+  public static int computeLexicographicDistance(String a, String b) {
     for (var i = 0; i < a.length(); ++i) {
       if (a.charAt(i) == b.charAt(i)) {
         continue;
diff --git a/lesson_07/objects/objects_app/src/main/java/com/codedifferently/lesson7/jordaneldridge/Animal.java b/lesson_07/objects/objects_app/src/main/java/com/codedifferently/lesson7/jordaneldridge/Animal.java
new file mode 100644
index 00000000..f273c76e
--- /dev/null
+++ b/lesson_07/objects/objects_app/src/main/java/com/codedifferently/lesson7/jordaneldridge/Animal.java
@@ -0,0 +1,132 @@
+package com.codedifferently.lesson7.jordaneldridge;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Animal {
+
+  public enum AnimalType {
+    MAMMAL,
+    BIRD,
+    REPTILE,
+    FISH,
+    AMPHIBIAN,
+    INSECT
+  }
+
+  private String name;
+  private boolean canBreathe;
+  private int age;
+  private String color;
+  private String sound;
+  private AnimalType type;
+  private static List<Animal> allAnimals = new ArrayList<>();
+
+  public Animal(
+      String name, boolean canBreathe, int age, String color, String sound, AnimalType type) {
+    this.name = name;
+    this.canBreathe = canBreathe;
+    this.age = age;
+    this.color = color;
+    this.sound = sound;
+    this.type = type;
+
+    allAnimals.add(this);
+  }
+
+  public static List<Animal> getAllAnimals() {
+    return allAnimals;
+  }
+
+  public String canFly() {
+    return (type == AnimalType.BIRD) ? "This animal can fly!" : "This animal cannot fly.";
+  }
+
+  public String makeSound() {
+    System.out.println("The " + this.name + " makes a sound!");
+    return this.sound;
+  }
+
+  public void growOlder() {
+    this.age += 1;
+    System.out.println("The " + this.name + " is now " + this.age + " years old.");
+  }
+
+  public void changeColor(String newColor) {
+    this.color = newColor;
+    System.out.println("The " + this.name + " has changed color to " + this.color + ".");
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public boolean getCanBreathe() {
+    return this.canBreathe;
+  }
+
+  public int getAge() {
+    return age;
+  }
+
+  public String getColor() {
+    return color;
+  }
+
+  public String getSound() {
+    return sound;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public void setCanBreathe(boolean canBreathe) {
+    this.canBreathe = canBreathe;
+  }
+
+  public void setAge(int age) throws InvalidAgeException {
+    if (age < 0) {
+      throw new InvalidAgeException("Age cannot be negative.");
+    }
+    this.age = age;
+  }
+
+  public void setColor(String color) {
+    this.color = color;
+  }
+
+  public void setSound(String sound) {
+    this.sound = sound;
+  }
+
+  public class InvalidAgeException extends Exception {
+    public InvalidAgeException(String message) {
+      super(message);
+    }
+  }
+
+  public void repeatSound(int times) {
+    for (int i = 0; i < times; i++) {
+      System.out.println(this.getSound());
+    }
+  }
+
+  public String toString() {
+    return "Animal [name="
+        + name
+        + ", canBreathe="
+        + canBreathe
+        + ", age="
+        + age
+        + ", color="
+        + color
+        + ", sound="
+        + sound
+        + "]";
+  }
+
+  public Object getType() {
+    return this.type;
+  }
+}
diff --git a/lesson_07/objects/objects_app/src/test/java/com/codedifferently/lesson7/jordaneldridge/AnimalTest.java b/lesson_07/objects/objects_app/src/test/java/com/codedifferently/lesson7/jordaneldridge/AnimalTest.java
new file mode 100644
index 00000000..9256f881
--- /dev/null
+++ b/lesson_07/objects/objects_app/src/test/java/com/codedifferently/lesson7/jordaneldridge/AnimalTest.java
@@ -0,0 +1,72 @@
+package com.codedifferently.lesson7.jordaneldridge;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.codedifferently.lesson7.jordaneldridge.Animal.AnimalType;
+import com.codedifferently.lesson7.jordaneldridge.Animal.InvalidAgeException;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+public class AnimalTest {
+
+  @Test
+  public void testConstructor() {
+    Animal animal = new Animal("Dog", true, 5, "Brown", "Bark", AnimalType.MAMMAL);
+    assertEquals("Dog", animal.getName());
+    assertTrue(animal.getCanBreathe());
+    assertEquals(5, animal.getAge());
+    assertEquals("Brown", animal.getColor());
+    assertEquals(AnimalType.MAMMAL, animal.getType());
+  }
+
+  @Test
+  public void testCanFly() {
+    Animal animal = new Animal("Owl", true, 1, "Brown", "whistles", AnimalType.BIRD);
+    assertEquals("This animal can fly!", animal.canFly());
+  }
+
+  @Test
+  public void testMakeSound() {
+    Animal animal = new Animal("lizard", true, 3, "Green", "Hissing", AnimalType.REPTILE);
+    String sound = animal.makeSound();
+    assertEquals("Hissing", sound);
+  }
+
+  @Test
+  public void testRepeatSound() {
+    Animal snake = new Animal("henry", true, 2, "brown", "hissing", AnimalType.REPTILE);
+    snake.repeatSound(2);
+  }
+
+  @Test
+  public void testSetAge() {
+    Animal animal = new Animal("Dog", true, 5, "Brown", "Bark", AnimalType.MAMMAL);
+    Exception exception =
+        assertThrows(
+            InvalidAgeException.class,
+            () -> {
+              animal.setAge(-1);
+            });
+
+    String expectedMessage = "Age cannot be negative.";
+    String actualMessage = exception.getMessage();
+
+    assertTrue(actualMessage.contains(expectedMessage));
+  }
+
+  @Test
+  public void testGetAllAnimals() {
+    Animal dog = new Animal("Josie", true, 5, "Brown", "Bark", AnimalType.MAMMAL);
+    Animal cat = new Animal("hunter", true, 3, "Black", "Meow", AnimalType.MAMMAL);
+    Animal bird = new Animal("Owl", true, 1, "Brown", "whistles", AnimalType.BIRD);
+
+    List<Animal> allAnimals = Animal.getAllAnimals();
+
+    assertTrue(allAnimals.contains(dog));
+    assertTrue(allAnimals.contains(cat));
+    assertTrue(allAnimals.contains(bird));
+    assertEquals(8, allAnimals.size());
+  }
+}
diff --git a/lesson_08/README.md b/lesson_08/README.md
new file mode 100644
index 00000000..66ae8239
--- /dev/null
+++ b/lesson_08/README.md
@@ -0,0 +1,15 @@
+# Lesson 08
+
+## Homework
+
+* Complete three [coding interview questions](#coding-interview-questions).
+
+## Coding Interview questions
+
+To complete this assignment, please implement the functions in [Lesson8.java][lesson-link] and submit a pull request with your solutions.
+
+* Find a cycle in a LinkedList.
+* Complete function that returns whether an array of elements contains a duplicate.
+* Write a function that returns the maximum path of a tree.
+
+[lesson-link]: ./collections/collections_app/src/main/java/com/codedifferently/lesson8/Lesson8.java
\ No newline at end of file
diff --git a/lesson_08/collections/.gitattributes b/lesson_08/collections/.gitattributes
new file mode 100644
index 00000000..097f9f98
--- /dev/null
+++ b/lesson_08/collections/.gitattributes
@@ -0,0 +1,9 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+
diff --git a/lesson_08/collections/.gitignore b/lesson_08/collections/.gitignore
new file mode 100644
index 00000000..1b6985c0
--- /dev/null
+++ b/lesson_08/collections/.gitignore
@@ -0,0 +1,5 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
diff --git a/lesson_08/collections/collections_app/build.gradle.kts b/lesson_08/collections/collections_app/build.gradle.kts
new file mode 100644
index 00000000..80529a15
--- /dev/null
+++ b/lesson_08/collections/collections_app/build.gradle.kts
@@ -0,0 +1,64 @@
+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    application
+    eclipse
+    id("com.diffplug.spotless") version "6.25.0"
+	  id("org.springframework.boot") version "3.2.2"
+    id("com.adarshr.test-logger") version "4.0.0"
+}
+
+apply(plugin = "io.spring.dependency-management")
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation("com.codedifferently.instructional:instructional-lib")
+    testImplementation("org.junit.jupiter:junit-jupiter:5.9.1")
+    testImplementation("org.springframework.boot:spring-boot-starter-test")
+    testImplementation("org.assertj:assertj-core:3.25.1")
+    testImplementation("at.favre.lib:bcrypt:0.10.2")
+
+    // This dependency is used by the application.
+    implementation("com.codedifferently.instructional:instructional-lib")
+    implementation("com.google.guava:guava:31.1-jre")
+    implementation("com.google.code.gson:gson:2.10.1")
+    implementation("org.projectlombok:lombok:1.18.30")
+    implementation("org.springframework.boot:spring-boot-starter")
+}
+
+application {
+    // Define the main class for the application.
+    mainClass.set("com.codedifferently.lesson8.Lesson8")
+}
+
+tasks.named<Test>("test") {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}
+
+
+configure<com.diffplug.gradle.spotless.SpotlessExtension> {
+
+  format("misc", {
+    // define the files to apply `misc` to
+    target("*.gradle", ".gitattributes", ".gitignore")
+
+    // define the steps to apply to those files
+    trimTrailingWhitespace()
+    indentWithTabs() // or spaces. Takes an integer argument if you don't like 4
+    endWithNewline()
+  })
+
+  java {
+    // don't need to set target, it is inferred from java
+
+    // apply a specific flavor of google-java-format
+    googleJavaFormat()
+    // fix formatting of type annotations
+    formatAnnotations()
+  }
+}
diff --git a/lesson_08/collections/collections_app/src/main/java/com/codedifferently/lesson8/Lesson8.java b/lesson_08/collections/collections_app/src/main/java/com/codedifferently/lesson8/Lesson8.java
new file mode 100644
index 00000000..252fba1f
--- /dev/null
+++ b/lesson_08/collections/collections_app/src/main/java/com/codedifferently/lesson8/Lesson8.java
@@ -0,0 +1,46 @@
+package com.codedifferently.lesson8;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@SpringBootApplication(scanBasePackages = "com.codedifferently")
+public class Lesson8 {
+
+  public static void main(String[] args) {
+    var application = new SpringApplication(Lesson8.class);
+    application.run(args);
+  }
+
+  public static boolean containsCycle(LinkedListNode head) {
+    return false;
+  }
+
+  public static int getMaximumBinaryTreeHeight(BinaryTreeNode root) {
+    return -1;
+  }
+
+  public static boolean containsDuplicates(String[] values) {
+    return false;
+  }
+
+  public static class LinkedListNode {
+    public LinkedListNode next;
+    public int val;
+
+    public LinkedListNode(int val) {
+      this.val = val;
+    }
+  }
+
+  public static class BinaryTreeNode {
+    public int val;
+    public BinaryTreeNode left;
+    public BinaryTreeNode right;
+
+    public BinaryTreeNode(int val) {
+      this.val = val;
+    }
+  }
+}
diff --git a/lesson_08/collections/collections_app/src/test/java/com/codedifferently/lesson8/Lesson8Test.java b/lesson_08/collections/collections_app/src/test/java/com/codedifferently/lesson8/Lesson8Test.java
new file mode 100644
index 00000000..e5f6ce18
--- /dev/null
+++ b/lesson_08/collections/collections_app/src/test/java/com/codedifferently/lesson8/Lesson8Test.java
@@ -0,0 +1,54 @@
+package com.codedifferently.lesson8;
+
+import static com.codedifferently.lesson8.Lesson8.BinaryTreeNode;
+import static com.codedifferently.lesson8.Lesson8.LinkedListNode;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class Lesson8Test {
+
+  @Test
+  void testCanVote() {
+    assertThat(new Lesson8()).isNotNull();
+  }
+
+  @Test
+  void testContainsCycle() {
+    LinkedListNode node1 = new LinkedListNode(1);
+    LinkedListNode node2 = new LinkedListNode(2);
+    LinkedListNode node3 = new LinkedListNode(3);
+    node1.next = node2;
+    node2.next = node3;
+    node3.next = node1;
+
+    boolean result = Lesson8.containsCycle(node1);
+
+    assertThat(result).isTrue();
+  }
+
+  @Test
+  void testGetMaximumBinaryTreeHeight() {
+    BinaryTreeNode root = new BinaryTreeNode(1);
+    BinaryTreeNode left = new BinaryTreeNode(2);
+    BinaryTreeNode right = new BinaryTreeNode(3);
+    root.left = left;
+    root.right = right;
+    left.left = new BinaryTreeNode(4);
+    left.right = new BinaryTreeNode(5);
+    right.left = new BinaryTreeNode(6);
+
+    int result = Lesson8.getMaximumBinaryTreeHeight(root);
+
+    assertThat(result).isEqualTo(3);
+  }
+
+  @Test
+  void testContainsDuplicates() {
+    String[] values = {"apple", "banana", "cherry", "apple"};
+
+    boolean result = Lesson8.containsDuplicates(values);
+
+    assertThat(result).isTrue();
+  }
+}
diff --git a/lesson_08/collections/gradle/wrapper/gradle-wrapper.jar b/lesson_08/collections/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 00000000..ccebba77
Binary files /dev/null and b/lesson_08/collections/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/lesson_08/collections/gradle/wrapper/gradle-wrapper.properties b/lesson_08/collections/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 00000000..bdc9a83b
--- /dev/null
+++ b/lesson_08/collections/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0.2-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/lesson_08/collections/gradlew b/lesson_08/collections/gradlew
new file mode 100755
index 00000000..79a61d42
--- /dev/null
+++ b/lesson_08/collections/gradlew
@@ -0,0 +1,244 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/lesson_08/collections/gradlew.bat b/lesson_08/collections/gradlew.bat
new file mode 100644
index 00000000..93e3f59f
--- /dev/null
+++ b/lesson_08/collections/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/lesson_08/collections/settings.gradle.kts b/lesson_08/collections/settings.gradle.kts
new file mode 100644
index 00000000..976f371b
--- /dev/null
+++ b/lesson_08/collections/settings.gradle.kts
@@ -0,0 +1,13 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/8.0.2/userguide/multi_project_builds.html
+ */
+
+includeBuild("../../lib/java/codedifferently-instructional")
+
+rootProject.name = "lesson_08"
+include("collections_app")
diff --git a/lesson_09/README.md b/lesson_09/README.md
new file mode 100644
index 00000000..042fa53c
--- /dev/null
+++ b/lesson_09/README.md
@@ -0,0 +1,35 @@
+# Lesson 09
+
+## Homework
+
+* Read [PIE][pie-book] 8; TPP 2.8–2.10
+* Read this [article on Test-Driven Development][tdd-article].
+* Complete [Library Management System](#library-management-system) assignment.
+
+## Library Management System
+
+For this assignment, you will build a library management system using object oriented principles. Pay attention to the requirements careful in order to implement your system successfully.
+
+### Functional Requirements
+
+* We want to define a book and keep track of its title, isbn, author(s), number of pages, and whether it is checked out or not.
+* We want define a patron with properties including their name and the books they have checked out.
+* We want to define a library that:
+    * Allows us to add/remove a book to and from its collection of books. 
+    * Allows us to register new patrons
+    * Allows us to check out books to patrons.
+    * Allows us to return books from patrons.
+
+### Technical Requirements
+
+* All of your types must be created in a unique sub-package under the `com.codedifferently.lesson9` namespace.
+* Include tests for all of your classes and public methods.
+* Include appropriate `javadoc` for your classes and methods. In VS Code, you can usually start a comment with `/**` and press `Enter` to let the IDE automatically create some starter text for you.
+
+### Tips
+
+* Read the functional requirements carefully, and take special care to identify *objects*, their *data*, and their *actions*.
+* It is highly recommended that you write your tests firsts, and then build what you need to make the tests work. This is essential to [Test-Driven Development][tdd-article].
+
+[pie-book]: https://github.com/shshankar1/ebooks/blob/master/Programming%20Interviews%20Exposed.PDF
+[tdd-article]: https://semaphoreci.com/blog/test-driven-development
diff --git a/lesson_09/oop/.gitattributes b/lesson_09/oop/.gitattributes
new file mode 100644
index 00000000..097f9f98
--- /dev/null
+++ b/lesson_09/oop/.gitattributes
@@ -0,0 +1,9 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+
diff --git a/lesson_09/oop/.gitignore b/lesson_09/oop/.gitignore
new file mode 100644
index 00000000..1b6985c0
--- /dev/null
+++ b/lesson_09/oop/.gitignore
@@ -0,0 +1,5 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
diff --git a/lesson_09/oop/gradle/wrapper/gradle-wrapper.jar b/lesson_09/oop/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 00000000..ccebba77
Binary files /dev/null and b/lesson_09/oop/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/lesson_09/oop/gradle/wrapper/gradle-wrapper.properties b/lesson_09/oop/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 00000000..bdc9a83b
--- /dev/null
+++ b/lesson_09/oop/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0.2-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/lesson_09/oop/gradlew b/lesson_09/oop/gradlew
new file mode 100755
index 00000000..79a61d42
--- /dev/null
+++ b/lesson_09/oop/gradlew
@@ -0,0 +1,244 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/lesson_09/oop/gradlew.bat b/lesson_09/oop/gradlew.bat
new file mode 100644
index 00000000..93e3f59f
--- /dev/null
+++ b/lesson_09/oop/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/lesson_09/oop/oop_app/build.gradle.kts b/lesson_09/oop/oop_app/build.gradle.kts
new file mode 100644
index 00000000..75d26ef3
--- /dev/null
+++ b/lesson_09/oop/oop_app/build.gradle.kts
@@ -0,0 +1,64 @@
+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    application
+    eclipse
+    id("com.diffplug.spotless") version "6.25.0"
+	  id("org.springframework.boot") version "3.2.2"
+    id("com.adarshr.test-logger") version "4.0.0"
+}
+
+apply(plugin = "io.spring.dependency-management")
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation("com.codedifferently.instructional:instructional-lib")
+    testImplementation("org.junit.jupiter:junit-jupiter:5.9.1")
+    testImplementation("org.springframework.boot:spring-boot-starter-test")
+    testImplementation("org.assertj:assertj-core:3.25.1")
+    testImplementation("at.favre.lib:bcrypt:0.10.2")
+
+    // This dependency is used by the application.
+    implementation("com.codedifferently.instructional:instructional-lib")
+    implementation("com.google.guava:guava:31.1-jre")
+    implementation("com.google.code.gson:gson:2.10.1")
+    implementation("org.projectlombok:lombok:1.18.30")
+    implementation("org.springframework.boot:spring-boot-starter")
+}
+
+application {
+    // Define the main class for the application.
+    mainClass.set("com.codedifferently.lesson9.Lesson9")
+}
+
+tasks.named<Test>("test") {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}
+
+
+configure<com.diffplug.gradle.spotless.SpotlessExtension> {
+
+  format("misc", {
+    // define the files to apply `misc` to
+    target("*.gradle", ".gitattributes", ".gitignore")
+
+    // define the steps to apply to those files
+    trimTrailingWhitespace()
+    indentWithTabs() // or spaces. Takes an integer argument if you don't like 4
+    endWithNewline()
+  })
+
+  java {
+    // don't need to set target, it is inferred from java
+
+    // apply a specific flavor of google-java-format
+    googleJavaFormat()
+    // fix formatting of type annotations
+    formatAnnotations()
+  }
+}
diff --git a/lesson_09/oop/oop_app/src/main/java/com/codedifferently/lesson9/Lesson9.java b/lesson_09/oop/oop_app/src/main/java/com/codedifferently/lesson9/Lesson9.java
new file mode 100644
index 00000000..4fe366e6
--- /dev/null
+++ b/lesson_09/oop/oop_app/src/main/java/com/codedifferently/lesson9/Lesson9.java
@@ -0,0 +1,15 @@
+package com.codedifferently.lesson9;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@SpringBootApplication(scanBasePackages = "com.codedifferently")
+public class Lesson9 {
+
+  public static void main(String[] args) {
+    var application = new SpringApplication(Lesson9.class);
+    application.run(args);
+  }
+}
diff --git a/lesson_09/oop/oop_app/src/test/java/com/codedifferently/lesson9/Lesson9Test.java b/lesson_09/oop/oop_app/src/test/java/com/codedifferently/lesson9/Lesson9Test.java
new file mode 100644
index 00000000..f37748cf
--- /dev/null
+++ b/lesson_09/oop/oop_app/src/test/java/com/codedifferently/lesson9/Lesson9Test.java
@@ -0,0 +1,13 @@
+package com.codedifferently.lesson9;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class Lesson9Test {
+
+  @Test
+  void testLesson9_create() {
+    assertThat(new Lesson9()).isNotNull();
+  }
+}
diff --git a/lesson_09/oop/settings.gradle.kts b/lesson_09/oop/settings.gradle.kts
new file mode 100644
index 00000000..3e39f49f
--- /dev/null
+++ b/lesson_09/oop/settings.gradle.kts
@@ -0,0 +1,13 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/8.0.2/userguide/multi_project_builds.html
+ */
+
+includeBuild("../../lib/java/codedifferently-instructional")
+
+rootProject.name = "lesson_09"
+include("oop_app")