diff --git a/Management/Models/Local/Quiz/LocalQuizQuestion.cs b/Management/Models/Local/Quiz/LocalQuizQuestion.cs
index ef7b7b1..cdf1631 100644
--- a/Management/Models/Local/Quiz/LocalQuizQuestion.cs
+++ b/Management/Models/Local/Quiz/LocalQuizQuestion.cs
@@ -1,4 +1,3 @@
-using System.Security.Cryptography;
 using System.Text.RegularExpressions;
 
 using Akka.Util.Internal;
diff --git a/nextjs/src/models/local/assignmnet/localAssignmentGroup.ts b/nextjs/src/models/local/assignmnet/localAssignmentGroup.ts
new file mode 100644
index 0000000..f83201c
--- /dev/null
+++ b/nextjs/src/models/local/assignmnet/localAssignmentGroup.ts
@@ -0,0 +1,6 @@
+export interface LocalAssignmentGroup {
+  canvasId?: number;
+  id: string;
+  name: string;
+  weight: number;
+}
\ No newline at end of file
diff --git a/nextjs/src/models/local/assignmnet/utils/assignmentMarkdownParser.ts b/nextjs/src/models/local/assignmnet/utils/assignmentMarkdownParser.ts
index 0def561..4b037c4 100644
--- a/nextjs/src/models/local/assignmnet/utils/assignmentMarkdownParser.ts
+++ b/nextjs/src/models/local/assignmnet/utils/assignmentMarkdownParser.ts
@@ -51,8 +51,8 @@ const parseSettings = (input: string) => {
   const submissionTypes = parseSubmissionTypes(input);
   const fileUploadExtensions = parseFileUploadExtensions(input);
 
-  const dueAt = timeUtils.parseDateOrThrow(rawDueAt, "DueAt");
-  const lockAt = timeUtils.parseDateOrUndefined(rawLockAt);
+  const dueAt = timeUtils.verifyDateOrThrow(rawDueAt, "DueAt");
+  const lockAt = timeUtils.verifyDateStringOrUndefined(rawLockAt);
 
   return {
     name,
diff --git a/nextjs/src/models/local/localCourse.ts b/nextjs/src/models/local/localCourse.ts
new file mode 100644
index 0000000..dc7dbd7
--- /dev/null
+++ b/nextjs/src/models/local/localCourse.ts
@@ -0,0 +1,45 @@
+import { LocalAssignmentGroup } from "./assignmnet/localAssignmentGroup";
+import { LocalModule } from "./localModules";
+
+export interface LocalCourse {
+  modules: LocalModule[];
+  settings: LocalCourseSettings;
+}
+
+export interface SimpleTimeOnly {
+  hour: number;
+  minute: number;
+}
+
+
+
+export interface LocalCourseSettings {
+  assignmentGroups: LocalAssignmentGroup[];
+  daysOfWeek: DayOfWeek[];
+  canvasId?: number;
+  startDate: string;
+  endDate: string;
+  defaultDueTime: SimpleTimeOnly;
+}
+
+export enum DayOfWeek {
+  Sunday = "Sunday",
+  Monday = "Monday",
+  Tuesday = "Tuesday",
+  Wednesday = "Wednesday",
+  Thursday = "Thursday",
+  Friday = "Friday",
+  Saturday = "Saturday",
+}
+
+
+// export const LocalCourseSettingsUtils = {
+//   toYaml(settings: LocalCourseSettings): string {
+//     return dump(settings, { noRefs: true });
+//   },
+
+//   parseYaml(rawText: string): LocalCourseSettings {
+//     const settings = load(rawText) as LocalCourseSettings;
+//     return createLocalCourseSettings(settings);
+//   },
+// };
\ No newline at end of file
diff --git a/nextjs/src/models/local/localModules.ts b/nextjs/src/models/local/localModules.ts
new file mode 100644
index 0000000..206b0c0
--- /dev/null
+++ b/nextjs/src/models/local/localModules.ts
@@ -0,0 +1,75 @@
+import { LocalAssignment } from "./assignmnet/localAssignment";
+import { IModuleItem } from "./IModuleItem";
+import { LocalCoursePage } from "./page/localCoursePage";
+import { LocalQuiz } from "./quiz/localQuiz";
+import { getDateFromString } from "./timeUtils";
+
+export interface LocalModule {
+  name: string;
+  assignments: LocalAssignment[];
+  quizzes: LocalQuiz[];
+  pages: LocalCoursePage[];
+}
+
+export const LocalModuleUtils = {
+  getSortedModuleItems(module: LocalModule): IModuleItem[] {
+    return [...module.assignments, ...module.quizzes, ...module.pages].sort(
+      (a, b) =>
+        (getDateFromString(a.dueAt)?.getTime() ?? 0) -
+        (getDateFromString(b.dueAt)?.getTime() ?? 0)
+    );
+  },
+
+  equals(module1: LocalModule, module2: LocalModule): boolean {
+    return (
+      module1.name.toLowerCase() === module2.name.toLowerCase() &&
+      LocalModuleUtils.compareCollections(
+        module1.assignments.sort((a, b) => a.name.localeCompare(b.name)),
+        module2.assignments.sort((a, b) => a.name.localeCompare(b.name))
+      ) &&
+      LocalModuleUtils.compareCollections(
+        module1.quizzes.sort((a, b) => a.name.localeCompare(b.name)),
+        module2.quizzes.sort((a, b) => a.name.localeCompare(b.name))
+      ) &&
+      LocalModuleUtils.compareCollections(
+        module1.pages.sort((a, b) => a.name.localeCompare(b.name)),
+        module2.pages.sort((a, b) => a.name.localeCompare(b.name))
+      )
+    );
+  },
+
+  compareCollections<T>(first: T[], second: T[]): boolean {
+    if (first.length !== second.length) return false;
+
+    for (let i = 0; i < first.length; i++) {
+      if (JSON.stringify(first[i]) !== JSON.stringify(second[i])) return false;
+    }
+
+    return true;
+  },
+
+  getHashCode(module: LocalModule): number {
+    const hash = new Map<string, number>();
+    hash.set(module.name.toLowerCase(), 1);
+    LocalModuleUtils.addRangeToHash(
+      hash,
+      module.assignments.sort((a, b) => a.name.localeCompare(b.name))
+    );
+    LocalModuleUtils.addRangeToHash(
+      hash,
+      module.quizzes.sort((a, b) => a.name.localeCompare(b.name))
+    );
+    LocalModuleUtils.addRangeToHash(
+      hash,
+      module.pages.sort((a, b) => a.name.localeCompare(b.name))
+    );
+
+    return Array.from(hash.values()).reduce((acc, val) => acc + val, 0);
+  },
+
+  addRangeToHash<T>(hash: Map<string, number>, items: T[]): void {
+    for (const item of items) {
+      hash.set(JSON.stringify(item), 1);
+    }
+  },
+};
diff --git a/nextjs/src/models/local/quiz/utils/quizMarkdownUtils.ts b/nextjs/src/models/local/quiz/utils/quizMarkdownUtils.ts
index 51ed193..76cc00c 100644
--- a/nextjs/src/models/local/quiz/utils/quizMarkdownUtils.ts
+++ b/nextjs/src/models/local/quiz/utils/quizMarkdownUtils.ts
@@ -1,4 +1,4 @@
-import { timeUtils } from "../../timeUtils";
+import { verifyDateOrThrow, verifyDateStringOrUndefined } from "../../timeUtils";
 import { LocalQuiz } from "../localQuiz";
 import { quizQuestionMarkdownUtils } from "./quizQuestionMarkdownUtils";
 
@@ -74,10 +74,10 @@ const getQuizWithOnlySettings = (settings: string): LocalQuiz => {
   );
 
   const rawDueAt = extractLabelValue(settings, "DueAt");
-  const dueAt = timeUtils.parseDateOrThrow(rawDueAt, "DueAt");
+  const dueAt = verifyDateOrThrow(rawDueAt, "DueAt");
 
   const rawLockAt = extractLabelValue(settings, "LockAt");
-  const lockAt = timeUtils.parseDateOrUndefined(rawLockAt);
+  const lockAt = verifyDateStringOrUndefined(rawLockAt);
 
   const description = extractDescription(settings);
   const localAssignmentGroupName = extractLabelValue(
diff --git a/nextjs/src/models/local/tests/markdown/assignmentMarkdown.test.ts b/nextjs/src/models/local/tests/assignmentMarkdown.test.ts
similarity index 93%
rename from nextjs/src/models/local/tests/markdown/assignmentMarkdown.test.ts
rename to nextjs/src/models/local/tests/assignmentMarkdown.test.ts
index 01efdc6..ea6afd8 100644
--- a/nextjs/src/models/local/tests/markdown/assignmentMarkdown.test.ts
+++ b/nextjs/src/models/local/tests/assignmentMarkdown.test.ts
@@ -1,8 +1,8 @@
 import { describe, it, expect } from "vitest";
-import { LocalAssignment } from "../../assignmnet/localAssignment";
-import { AssignmentSubmissionType } from "../../assignmnet/assignmentSubmissionType";
-import { assignmentMarkdownSerializer } from "../../assignmnet/utils/assignmentMarkdownSerializer";
-import { assignmentMarkdownParser } from "../../assignmnet/utils/assignmentMarkdownParser";
+import { LocalAssignment } from "../assignmnet/localAssignment";
+import { AssignmentSubmissionType } from "../assignmnet/assignmentSubmissionType";
+import { assignmentMarkdownSerializer } from "../assignmnet/utils/assignmentMarkdownSerializer";
+import { assignmentMarkdownParser } from "../assignmnet/utils/assignmentMarkdownParser";
 
 describe("AssignmentMarkdownTests", () => {
   it("can parse assignment settings", () => {
diff --git a/nextjs/src/models/local/tests/markdown/pageMarkdown.test.ts b/nextjs/src/models/local/tests/pageMarkdown.test.ts
similarity index 77%
rename from nextjs/src/models/local/tests/markdown/pageMarkdown.test.ts
rename to nextjs/src/models/local/tests/pageMarkdown.test.ts
index 6a63ab0..bc5da5c 100644
--- a/nextjs/src/models/local/tests/markdown/pageMarkdown.test.ts
+++ b/nextjs/src/models/local/tests/pageMarkdown.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { LocalCoursePage } from "../../page/localCoursePage";
-import { pageMarkdownUtils } from "../../page/pageMarkdownUtils";
+import { LocalCoursePage } from "../page/localCoursePage";
+import { pageMarkdownUtils } from "../page/pageMarkdownUtils";
 
 describe("PageMarkdownTests", () => {
   it("can parse page", () => {
diff --git a/nextjs/src/models/local/tests/markdown/quiz/matchingAnswers.test.ts b/nextjs/src/models/local/tests/quizMarkdown/matchingAnswers.test.ts
similarity index 97%
rename from nextjs/src/models/local/tests/markdown/quiz/matchingAnswers.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/matchingAnswers.test.ts
index 7325537..d8c0351 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/matchingAnswers.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/matchingAnswers.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { QuestionType } from "../../../../../models/local/quiz/localQuizQuestion";
+import { QuestionType } from "../../quiz/localQuizQuestion";
 import { quizMarkdownUtils } from "@/models/local/quiz/utils/quizMarkdownUtils";
 import { quizQuestionMarkdownUtils } from "@/models/local/quiz/utils/quizQuestionMarkdownUtils";
 
diff --git a/nextjs/src/models/local/tests/markdown/quiz/multipleAnswers.test.ts b/nextjs/src/models/local/tests/quizMarkdown/multipleAnswers.test.ts
similarity index 94%
rename from nextjs/src/models/local/tests/markdown/quiz/multipleAnswers.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/multipleAnswers.test.ts
index ffaf836..23acdc6 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/multipleAnswers.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/multipleAnswers.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { LocalQuiz } from "../../../../../models/local/quiz/localQuiz";
-import { QuestionType } from "../../../../../models/local/quiz/localQuizQuestion";
+import { LocalQuiz } from "../../quiz/localQuiz";
+import { QuestionType } from "../../quiz/localQuizQuestion";
 import { quizMarkdownUtils } from "@/models/local/quiz/utils/quizMarkdownUtils";
 import { quizQuestionMarkdownUtils } from "@/models/local/quiz/utils/quizQuestionMarkdownUtils";
 
@@ -26,7 +26,7 @@ describe("MultipleAnswersTests", () => {
             { correct: true, text: "false" },
             { correct: false, text: "neither" },
           ],
-          matchDistractors: []
+          matchDistractors: [],
         },
       ],
     };
diff --git a/nextjs/src/models/local/tests/markdown/quiz/multipleChoice.test.ts b/nextjs/src/models/local/tests/quizMarkdown/multipleChoice.test.ts
similarity index 83%
rename from nextjs/src/models/local/tests/markdown/quiz/multipleChoice.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/multipleChoice.test.ts
index 1ebe12f..8bb6584 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/multipleChoice.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/multipleChoice.test.ts
@@ -1,10 +1,7 @@
 import { describe, it, expect } from "vitest";
-import { LocalQuiz } from "../../../../../models/local/quiz/localQuiz";
-import {
-  LocalQuizQuestion,
-  QuestionType,
-} from "../../../../../models/local/quiz/localQuizQuestion";
-import { LocalQuizQuestionAnswer } from "../../../../../models/local/quiz/localQuizQuestionAnswer";
+import { LocalQuiz } from "../../quiz/localQuiz";
+import { LocalQuizQuestion, QuestionType } from "../../quiz/localQuizQuestion";
+import { LocalQuizQuestionAnswer } from "../../quiz/localQuizQuestionAnswer";
 import { quizMarkdownUtils } from "@/models/local/quiz/utils/quizMarkdownUtils";
 import { quizQuestionMarkdownUtils } from "@/models/local/quiz/utils/quizQuestionMarkdownUtils";
 
@@ -37,7 +34,7 @@ lines
             { correct: true, text: "true" },
             { correct: false, text: "false\n\nendline" },
           ],
-          matchDistractors: []
+          matchDistractors: [],
         },
       ],
     };
diff --git a/nextjs/src/models/local/tests/markdown/quiz/quizDeterministicChecks.test.ts b/nextjs/src/models/local/tests/quizMarkdown/quizDeterministicChecks.test.ts
similarity index 96%
rename from nextjs/src/models/local/tests/markdown/quiz/quizDeterministicChecks.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/quizDeterministicChecks.test.ts
index 479a8b2..eab3500 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/quizDeterministicChecks.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/quizDeterministicChecks.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { LocalQuiz } from "../../../../../models/local/quiz/localQuiz";
-import { quizMarkdownUtils } from "../../../../../models/local/quiz/utils/quizMarkdownUtils";
+import { LocalQuiz } from "../../quiz/localQuiz";
+import { quizMarkdownUtils } from "../../quiz/utils/quizMarkdownUtils";
 import { QuestionType } from "@/models/local/quiz/localQuizQuestion";
 
 // Test suite for deterministic checks on LocalQuiz
@@ -88,7 +88,7 @@ describe("QuizDeterministicChecks", () => {
           questionType: QuestionType.ESSAY,
           points: 1,
           matchDistractors: [],
-          answers: []
+          answers: [],
         },
       ],
       allowedAttempts: -1,
diff --git a/nextjs/src/models/local/tests/markdown/quiz/quizMarkdown.test.ts b/nextjs/src/models/local/tests/quizMarkdown/quizMarkdown.test.ts
similarity index 97%
rename from nextjs/src/models/local/tests/markdown/quiz/quizMarkdown.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/quizMarkdown.test.ts
index 834bce8..44afcb4 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/quizMarkdown.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/quizMarkdown.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { LocalQuiz } from "../../../../../models/local/quiz/localQuiz";
-import { quizMarkdownUtils } from "../../../../../models/local/quiz/utils/quizMarkdownUtils";
+import { LocalQuiz } from "../../quiz/localQuiz";
+import { quizMarkdownUtils } from "../../quiz/utils/quizMarkdownUtils";
 import { QuestionType } from "@/models/local/quiz/localQuizQuestion";
 import { quizQuestionMarkdownUtils } from "@/models/local/quiz/utils/quizQuestionMarkdownUtils";
 
diff --git a/nextjs/src/models/local/tests/markdown/quiz/testAnswer.test.ts b/nextjs/src/models/local/tests/quizMarkdown/testAnswer.test.ts
similarity index 74%
rename from nextjs/src/models/local/tests/markdown/quiz/testAnswer.test.ts
rename to nextjs/src/models/local/tests/quizMarkdown/testAnswer.test.ts
index a97b709..b9b37de 100644
--- a/nextjs/src/models/local/tests/markdown/quiz/testAnswer.test.ts
+++ b/nextjs/src/models/local/tests/quizMarkdown/testAnswer.test.ts
@@ -1,10 +1,10 @@
-import { QuestionType } from '../../../../../models/local/quiz/localQuizQuestion';
-import { quizMarkdownUtils } from '../../../../../models/local/quiz/utils/quizMarkdownUtils';
-import { quizQuestionMarkdownUtils } from '../../../../../models/local/quiz/utils/quizQuestionMarkdownUtils';
-import { describe, it, expect } from 'vitest';
+import { QuestionType } from "../../quiz/localQuizQuestion";
+import { quizMarkdownUtils } from "../../quiz/utils/quizMarkdownUtils";
+import { quizQuestionMarkdownUtils } from "../../quiz/utils/quizQuestionMarkdownUtils";
+import { describe, it, expect } from "vitest";
 
-describe('TextAnswerTests', () => {
-  it('can parse essay', () => {
+describe("TextAnswerTests", () => {
+  it("can parse essay", () => {
     const rawMarkdownQuiz = `
 Name: Test Quiz
 ShuffleAnswers: true
@@ -26,10 +26,10 @@ essay
 
     expect(firstQuestion.points).toBe(1);
     expect(firstQuestion.questionType).toBe(QuestionType.ESSAY);
-    expect(firstQuestion.text).not.toContain('essay');
+    expect(firstQuestion.text).not.toContain("essay");
   });
 
-  it('can parse short answer', () => {
+  it("can parse short answer", () => {
     const rawMarkdownQuiz = `
 Name: Test Quiz
 ShuffleAnswers: true
@@ -51,10 +51,10 @@ short answer
 
     expect(firstQuestion.points).toBe(1);
     expect(firstQuestion.questionType).toBe(QuestionType.SHORT_ANSWER);
-    expect(firstQuestion.text).not.toContain('short answer');
+    expect(firstQuestion.text).not.toContain("short answer");
   });
 
-  it('short answer to markdown is correct', () => {
+  it("short answer to markdown is correct", () => {
     const rawMarkdownQuiz = `
 Name: Test Quiz
 ShuffleAnswers: true
@@ -74,14 +74,15 @@ short answer
     const quiz = quizMarkdownUtils.parseMarkdown(rawMarkdownQuiz);
     const firstQuestion = quiz.questions[0];
 
-    const questionMarkdown = quizQuestionMarkdownUtils.toMarkdown(firstQuestion);
+    const questionMarkdown =
+      quizQuestionMarkdownUtils.toMarkdown(firstQuestion);
     const expectedMarkdown = `Points: 1
 Which events are triggered when the user clicks on an input field?
 short_answer`;
     expect(questionMarkdown).toContain(expectedMarkdown);
   });
 
-  it('essay question to markdown is correct', () => {
+  it("essay question to markdown is correct", () => {
     const rawMarkdownQuiz = `
 Name: Test Quiz
 ShuffleAnswers: true
@@ -101,7 +102,8 @@ essay
     const quiz = quizMarkdownUtils.parseMarkdown(rawMarkdownQuiz);
     const firstQuestion = quiz.questions[0];
 
-    const questionMarkdown = quizQuestionMarkdownUtils.toMarkdown(firstQuestion);
+    const questionMarkdown =
+      quizQuestionMarkdownUtils.toMarkdown(firstQuestion);
     const expectedMarkdown = `Points: 1
 Which events are triggered when the user clicks on an input field?
 essay`;
diff --git a/nextjs/src/models/local/tests/markdown/rubricMarkdown.test.ts b/nextjs/src/models/local/tests/rubricMarkdown.test.ts
similarity index 93%
rename from nextjs/src/models/local/tests/markdown/rubricMarkdown.test.ts
rename to nextjs/src/models/local/tests/rubricMarkdown.test.ts
index 84d8fe9..8fc6543 100644
--- a/nextjs/src/models/local/tests/markdown/rubricMarkdown.test.ts
+++ b/nextjs/src/models/local/tests/rubricMarkdown.test.ts
@@ -1,9 +1,6 @@
 import { describe, it, expect } from "vitest";
-import {
-  RubricItem,
-  rubricItemIsExtraCredit,
-} from "../../assignmnet/rubricItem";
-import { assignmentMarkdownParser } from "../../assignmnet/utils/assignmentMarkdownParser";
+import { RubricItem, rubricItemIsExtraCredit } from "../assignmnet/rubricItem";
+import { assignmentMarkdownParser } from "../assignmnet/utils/assignmentMarkdownParser";
 
 describe("RubricMarkdownTests", () => {
   it("can parse one item", () => {
diff --git a/nextjs/src/models/local/timeUtils.ts b/nextjs/src/models/local/timeUtils.ts
index 941774a..ec17d00 100644
--- a/nextjs/src/models/local/timeUtils.ts
+++ b/nextjs/src/models/local/timeUtils.ts
@@ -1,12 +1,13 @@
-const parseDateOrUndefined = (value: string): string | undefined => {
 
+
+export const getDateFromString = (value: string) => {
   // may need to check for other formats
-  const validDateRegex = /([1-9][1-9]|[0-2])\/(0[1-9]|[1-2][0-9]|3[01])\/\d{4} (0[0-9]|1[0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])/;
+  const validDateRegex =
+    /([1-9][1-9]|[0-2])\/(0[1-9]|[1-2][0-9]|3[01])\/\d{4} (0[0-9]|1[0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])/;
   if (!validDateRegex.test(value)) {
     return undefined;
   }
 
-
   const [datePart, timePart] = value.split(" ");
   const [day, month, year] = datePart.split("/").map(Number);
   const [hours, minutes, seconds] = timePart.split(":").map(Number);
@@ -15,6 +16,26 @@ const parseDateOrUndefined = (value: string): string | undefined => {
   if (isNaN(date.getTime())) {
     return undefined;
   }
+  return date;
+};
+
+export const verifyDateStringOrUndefined = (
+  value: string
+): string | undefined => {
+  const date = getDateFromString(value);
+  return date ? dateToMarkdownString(date) : undefined;
+};
+
+export const verifyDateOrThrow = (
+  value: string,
+  labelForError: string
+): string => {
+  const myDate = verifyDateStringOrUndefined(value);
+  if (!myDate) throw new Error(`Invalid format for ${labelForError}: ${value}`);
+  return myDate;
+};
+
+export const dateToMarkdownString = (date: Date) => {
   const stringDay = String(date.getDate()).padStart(2, "0");
   const stringMonth = String(date.getMonth() + 1).padStart(2, "0"); // Months are zero-based
   const stringYear = date.getFullYear();
@@ -24,12 +45,3 @@ const parseDateOrUndefined = (value: string): string | undefined => {
 
   return `${stringDay}/${stringMonth}/${stringYear} ${stringHours}:${stringMinutes}:${stringSeconds}`;
 };
-
-export const timeUtils = {
-  parseDateOrUndefined,
-  parseDateOrThrow: (value: string, labelForError: string): string => {
-    const myDate = parseDateOrUndefined(value);
-    if (!myDate) throw new Error(`Invalid format for ${labelForError}: ${value}`);
-    return myDate;
-  },
-};
diff --git a/nextjs/src/services/fileStorage/courseDifferences.ts b/nextjs/src/services/fileStorage/courseDifferences.ts
new file mode 100644
index 0000000..b572975
--- /dev/null
+++ b/nextjs/src/services/fileStorage/courseDifferences.ts
@@ -0,0 +1,152 @@
+import { LocalCourse, LocalCourseSettings } from "@/models/local/localCourse";
+import { LocalModule } from "@/models/local/localModules";
+
+export const CourseDifferences = {
+  getDeletedChanges(
+    newCourse: LocalCourse,
+    oldCourse: LocalCourse
+  ): DeleteCourseChanges {
+    if (newCourse === oldCourse) {
+      const emptyDeletes: DeleteCourseChanges = {
+        namesOfModulesToDeleteCompletely: [],
+        deleteContentsOfModule: [],
+      };
+      return emptyDeletes;
+    }
+
+    const moduleNamesNoLongerReferenced = oldCourse.modules
+      .filter(
+        (oldModule) =>
+          !newCourse.modules.some(
+            (newModule) => newModule.name === oldModule.name
+          )
+      )
+      .map((oldModule) => oldModule.name);
+
+    const modulesWithDeletions = oldCourse.modules
+      .filter(
+        (oldModule) =>
+          !newCourse.modules.some(
+            (newModule) =>
+              JSON.stringify(newModule) === JSON.stringify(oldModule)
+          )
+      )
+      .map((oldModule) => {
+        const newModule = newCourse.modules.find(
+          (m) => m.name === oldModule.name
+        );
+        if (!newModule) return oldModule;
+
+        const unreferencedAssignments = oldModule.assignments.filter(
+          (oldAssignment) =>
+            !newModule.assignments.some(
+              (newAssignment) => newAssignment.name === oldAssignment.name
+            )
+        );
+        const unreferencedQuizzes = oldModule.quizzes.filter(
+          (oldQuiz) =>
+            !newModule.quizzes.some((newQuiz) => newQuiz.name === oldQuiz.name)
+        );
+        const unreferencedPages = oldModule.pages.filter(
+          (oldPage) =>
+            !newModule.pages.some((newPage) => newPage.name === oldPage.name)
+        );
+
+        return {
+          ...oldModule,
+          assignments: unreferencedAssignments,
+          quizzes: unreferencedQuizzes,
+          pages: unreferencedPages,
+        };
+      });
+
+    return {
+      namesOfModulesToDeleteCompletely: moduleNamesNoLongerReferenced,
+      deleteContentsOfModule: modulesWithDeletions,
+    };
+  },
+
+  getNewChanges(
+    newCourse: LocalCourse,
+    oldCourse: LocalCourse
+  ): NewCourseChanges {
+    if (newCourse === oldCourse) {
+      const emptyChanges: NewCourseChanges = {
+        modules: [],
+      };
+      return emptyChanges;
+    }
+
+    const differentModules = newCourse.modules
+      .filter(
+        (newModule) =>
+          !oldCourse.modules.some(
+            (oldModule) =>
+              JSON.stringify(oldModule) === JSON.stringify(newModule)
+          )
+      )
+      .map((newModule) => {
+        const oldModule = oldCourse.modules.find(
+          (m) => m.name === newModule.name
+        );
+        if (!oldModule) return newModule;
+
+        const newAssignments = newModule.assignments.filter(
+          (newAssignment) =>
+            !oldModule.assignments.some(
+              (oldAssignment) =>
+                JSON.stringify(newAssignment) === JSON.stringify(oldAssignment)
+            )
+        );
+        const newQuizzes = newModule.quizzes.filter(
+          (newQuiz) =>
+            !oldModule.quizzes.some(
+              (oldQuiz) => JSON.stringify(newQuiz) === JSON.stringify(oldQuiz)
+            )
+        );
+        const newPages = newModule.pages.filter(
+          (newPage) =>
+            !oldModule.pages.some(
+              (oldPage) => JSON.stringify(newPage) === JSON.stringify(oldPage)
+            )
+        );
+
+        return {
+          ...newModule,
+          assignments: newAssignments,
+          quizzes: newQuizzes,
+          pages: newPages,
+        };
+      });
+
+    return {
+      settings: newCourse.settings,
+      modules: differentModules,
+    };
+  },
+};
+
+export interface DeleteCourseChanges {
+  namesOfModulesToDeleteCompletely: string[];
+  deleteContentsOfModule: LocalModule[];
+}
+
+export interface NewCourseChanges {
+  modules: LocalModule[];
+  settings?: LocalCourseSettings;
+}
+
+// Default values for DeleteCourseChanges and NewCourseChanges
+// export const createDeleteCourseChanges = (
+//   init?: Partial<DeleteCourseChanges>
+// ): DeleteCourseChanges => ({
+//   namesOfModulesToDeleteCompletely: init?.namesOfModulesToDeleteCompletely ?? [],
+//   deleteContentsOfModule: init?.deleteContentsOfModule ?? [],
+// });
+
+// export const createNewCourseChanges = (
+//   init?: Partial<NewCourseChanges>
+// ): NewCourseChanges => ({
+//   modules: init?.modules ?? [],
+//   settings: init?.settings,
+// });
diff --git a/nextjs/src/services/tests/courseDifferencesDeletions.test.ts b/nextjs/src/services/tests/courseDifferencesDeletions.test.ts
new file mode 100644
index 0000000..6645804
--- /dev/null
+++ b/nextjs/src/services/tests/courseDifferencesDeletions.test.ts
@@ -0,0 +1,423 @@
+import { describe, it, expect } from "vitest";
+import { LocalCourse } from "@/models/local/localCourse";
+import { CourseDifferences } from "../fileStorage/courseDifferences";
+
+describe("CourseDifferencesDeletionsTests", () => {
+  it("same module does not get deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.namesOfModulesToDeleteCompletely).toHaveLength(0);
+  });
+
+  it("changed module - old one gets deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module 2",
+          assignments: [],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.namesOfModulesToDeleteCompletely).toHaveLength(1);
+    expect(differences.namesOfModulesToDeleteCompletely[0]).toBe("test module");
+  });
+
+  it("new assignment name gets deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment changed name",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.namesOfModulesToDeleteCompletely).toHaveLength(0);
+    expect(differences.deleteContentsOfModule).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].assignments).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].assignments[0].name).toBe(
+      "test assignment"
+    );
+  });
+
+  it("assignments with changed descriptions do not get deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.deleteContentsOfModule).toHaveLength(0);
+  });
+
+  it("can detect changed and unchanged assignments", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+            {
+              name: "test assignment 2",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [
+            {
+              name: "test assignment",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+            {
+              name: "test assignment 2 changed",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              submissionTypes: [],
+              allowedFileUploadExtensions: [],
+              rubric: []
+            },
+          ],
+          quizzes: [],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.deleteContentsOfModule).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].assignments).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].assignments[0].name).toBe(
+      "test assignment 2"
+    );
+  });
+
+  it("changed quizzes get deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [
+            {
+              name: "Test Quiz",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              shuffleAnswers: false,
+              showCorrectAnswers: false,
+              oneQuestionAtATime: false,
+              allowedAttempts: 0,
+              questions: []
+            },
+            {
+              name: "Test Quiz 2",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              shuffleAnswers: false,
+              showCorrectAnswers: false,
+              oneQuestionAtATime: false,
+              allowedAttempts: 0,
+              questions: []
+            },
+          ],
+          pages: [],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [
+            {
+              name: "Test Quiz",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              shuffleAnswers: false,
+              showCorrectAnswers: false,
+              oneQuestionAtATime: false,
+              allowedAttempts: 0,
+              questions: []
+            },
+            {
+              name: "Test Quiz 3",
+              description: "test description",
+              dueAt: "09/07/2024 23:59:00",
+              shuffleAnswers: false,
+              showCorrectAnswers: false,
+              oneQuestionAtATime: false,
+              allowedAttempts: 0,
+              questions: []
+            },
+          ],
+          pages: [],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.deleteContentsOfModule).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].quizzes).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].quizzes[0].name).toBe(
+      "Test Quiz 2"
+    );
+  });
+
+  it("changed pages get deleted", () => {
+    const oldCourse: LocalCourse = {
+      settings: {
+        assignmentGroups: [],
+        daysOfWeek: [],
+        startDate: "09/07/2024 23:59:00",
+        endDate: "09/07/2024 23:59:00",
+        defaultDueTime: {
+          hour: 23,
+          minute: 59,
+        },
+      },
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [],
+          pages: [
+            {
+              name: "Test Page",
+              text: "test contents",
+              dueAt: "09/07/2024 23:59:00",
+            },
+            {
+              name: "Test Page 2",
+              text: "test contents",
+              dueAt: "09/07/2024 23:59:00"
+            },
+          ],
+        },
+      ],
+    };
+    const newCourse: LocalCourse = {
+      ...oldCourse,
+      modules: [
+        {
+          name: "test module",
+          assignments: [],
+          quizzes: [],
+          pages: [
+            {
+              name: "Test Page",
+              text: "test contents",
+              dueAt: "09/07/2024 23:59:00"
+            },
+            {
+              name: "Test Page 3",
+              text: "test contents",
+              dueAt: "09/07/2024 23:59:00"
+            },
+          ],
+        },
+      ],
+    };
+
+    const differences = CourseDifferences.getDeletedChanges(newCourse, oldCourse);
+
+    expect(differences.deleteContentsOfModule).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].pages).toHaveLength(1);
+    expect(differences.deleteContentsOfModule[0].pages[0].name).toBe(
+      "Test Page 2"
+    );
+  });
+});