diff --git a/app/models/assignment.rb b/app/models/assignment.rb
new file mode 100644
index 0000000..acb9437
--- /dev/null
+++ b/app/models/assignment.rb
@@ -0,0 +1,7 @@
+class Assignment < ApplicationRecord
+    #Relationship with Lms
+    belongs_to :lms
+
+    #Relationship with Extension
+    has_many :extensions
+end
\ No newline at end of file
diff --git a/app/models/course.rb b/app/models/course.rb
index d1af702..41de79c 100644
--- a/app/models/course.rb
+++ b/app/models/course.rb
@@ -1,4 +1,5 @@
 class Course < ApplicationRecord
+
   # Associations
   has_many :course_to_lmss
   has_many :lmss, through: :course_to_lmss
@@ -7,4 +8,5 @@ class Course < ApplicationRecord
   
   # Validations
   validates :course_name, presence: true
+
 end
\ No newline at end of file
diff --git a/app/models/course_to_lms.rb b/app/models/course_to_lms.rb
index 04faa5a..8496251 100644
--- a/app/models/course_to_lms.rb
+++ b/app/models/course_to_lms.rb
@@ -1,4 +1,5 @@
 class CourseToLms < ApplicationRecord
+
   # Associations
   belongs_to :course
   belongs_to :lms
@@ -6,4 +7,5 @@ class CourseToLms < ApplicationRecord
   # Validations
   validates :course_id, presence: true
   validates :lms_id, presence: true
+
 end
\ No newline at end of file
diff --git a/app/models/extension.rb b/app/models/extension.rb
new file mode 100644
index 0000000..ea5f41b
--- /dev/null
+++ b/app/models/extension.rb
@@ -0,0 +1,7 @@
+class Extension < ApplicationRecord
+    #Relationship with Assignment
+    belongs_to :assignment
+
+    #Relationship with User
+    has_one :user
+end
\ No newline at end of file
diff --git a/app/models/lms.rb b/app/models/lms.rb
new file mode 100644
index 0000000..743cdcb
--- /dev/null
+++ b/app/models/lms.rb
@@ -0,0 +1,8 @@
+class Lms < ApplicationRecord
+    #Relationship with Course (and CourseToLms)
+    has_many :course_to_lmss
+    has_many :courses, :through => :course_to_lmss
+
+    #Relationship with Assignment
+    has_many :assignments
+end
\ No newline at end of file
diff --git a/app/models/user.rb b/app/models/user.rb
index a17da6f..c88fc18 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -3,8 +3,13 @@ class User < ApplicationRecord
     validates :email, presence: true, uniqueness: true
     validates :email, format: { with: URI::MailTo::EMAIL_REGEXP, message: 'must be a valid email address' }
 
-    # Associasions
+    # Associations
     has_many :lms_credentials, dependent: :destroy
-    has_many :user_to_courses
+
+    # Relationship with Extension
     has_many :extensions
+
+    #Relationship with Course (and UserToCourse)
+    has_many :user_to_courses
+    has_many :courses, :through => :user_to_courses
   end
\ No newline at end of file
diff --git a/app/models/user_to_course.rb b/app/models/user_to_course.rb
new file mode 100644
index 0000000..e7fee1c
--- /dev/null
+++ b/app/models/user_to_course.rb
@@ -0,0 +1,4 @@
+class UserToCourse < ApplicationRecord
+    belongs_to :user
+    belongs_to :course
+end
\ No newline at end of file
diff --git a/db/seeds.rb b/db/seeds.rb
index 4fbd6ed..dc36945 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -7,3 +7,86 @@
 #   ["Action", "Comedy", "Drama", "Horror"].each do |genre_name|
 #     MovieGenre.find_or_create_by!(name: genre_name)
 #   end
+
+LmsCredential.destroy_all
+Extension.destroy_all
+Assignment.destroy_all
+CourseToLms.destroy_all
+UserToCourse.destroy_all
+Course.destroy_all
+Lms.destroy_all
+User.destroy_all
+
+canvas = Lms.create!({
+    lms_name: "Canvas",
+    use_auth_token: true
+})
+
+
+test_assignment = Assignment.create!({
+  lms_id: canvas.id,
+  name: "Test Assignment",
+  external_assignment_id: "11111"
+})
+
+
+test_course = Course.create!({
+  course_name: "Test Course",
+})
+
+test_course_to_lms = CourseToLms.create!({
+  lms_id: canvas.id,
+  course_id: test_course.id,
+  external_course_id: "22222"
+})
+
+test_user = User.create!({
+  email: "testuser@example.com",
+})
+
+test_user_to_course = UserToCourse.create!({
+  user_id: test_user.id,
+  course_id: test_course.id,
+  role: "test"
+})
+
+test_extension = Extension.create!({
+  assignment_id: test_assignment.id,
+  student_email: "teststudent@example.com",
+  initial_due_date: DateTime.iso8601('2024-04-20'),
+  new_due_date: DateTime.iso8601('2024-04-30'),
+  last_processed_by_id: test_user.id,
+  external_extension_id: "33333"
+})
+
+test_lms_credential = LmsCredential.create!({
+  user_id: test_user.id,
+  lms_name: "canvas",
+  token: "test token",
+  external_user_id: "44444"
+})
+
+real_course = Course.create!({
+  course_name: "CS169L Flextension",
+})
+
+real_course_to_lms = CourseToLms.create!({
+  lms_id: canvas.id,
+  course_id: real_course.id,
+  external_course_id: "1534405"
+})
+
+real_assignment = Assignment.create!({
+  lms_id: canvas.id,
+  name: "Seed Data Testing",
+  external_assignment_id: "8741483"
+})
+
+real_extension = Extension.create!({
+  assignment_id: real_assignment.id,
+  student_email: "teststudent@example.com",
+  initial_due_date: DateTime.iso8601('2024-04-20'),
+  new_due_date: DateTime.iso8601('2024-04-27'),
+  last_processed_by_id: test_user.id,
+  external_extension_id: "270163"
+})
\ No newline at end of file