diff --git a/app/controllers/api/lessons/batch_controller.rb b/app/controllers/api/lessons/batch_controller.rb
index cd759f03b..6562389b3 100644
--- a/app/controllers/api/lessons/batch_controller.rb
+++ b/app/controllers/api/lessons/batch_controller.rb
@@ -10,13 +10,15 @@ class BatchController < ApiController
       before_action :verify_school_class_belongs_to_school
       before_action :verify_can_create_scratch_projects
       before_action :authorize_lesson_projects!
+      before_action :authorize_source_projects!
 
       def create_batch
         authorize_blank_lesson_batch! unless lesson_projects?
         raise ParameterError, 'lesson_projects cannot be blank' unless lesson_projects?
 
         @results = Lesson::CreateBatch.call(
-          lessons_params: batch_lessons_params
+          lessons_params: batch_lessons_params,
+          source_projects: batch_source_projects
         )
         @user = current_user
         @results.select(&:success?).each { |result| track_project_event('Project - Created', result[:lesson].project) }
@@ -34,18 +36,35 @@ def verify_school_class_belongs_to_school
       def verify_can_create_scratch_projects
         return unless lesson_projects?
 
-        scratch_project_params = params[:lesson_projects].find { |lesson_params| scratch_project?(lesson_params) }
-        return unless scratch_project_params
-
-        verify_lesson_scratch!(scratch_project_params)
+        batch_lessons_params.each_index do |index|
+          verify_lesson_scratch!(batch_lessons_params[index], source_project: source_project_for(index))
+          break if performed?
+        end
       end
 
       def batch_lessons_params
         @batch_lessons_params ||= params[:lesson_projects].map { |lesson_params| create_batch_params(lesson_params) }
       end
 
+      def batch_source_projects
+        batch_lessons_params.each_index.map { |index| source_project_for(index) }
+      end
+
+      def source_project_for(index)
+        @source_project_by_index ||= {}
+        return @source_project_by_index[index] if @source_project_by_index.key?(index)
+
+        lesson_params = batch_lessons_params[index]
+        @source_project_by_index[index] = find_source_project!(
+          lesson_params[:source_project_identifier],
+          lesson_params.dig(:project_attributes, :locale)
+        )
+      end
+
       def create_batch_params(lesson_project)
-        lesson_project.permit(*LESSON_ATTRIBUTES, :origin_identifier, project_attributes: PROJECT_ATTRIBUTES).merge(user_id: current_user.id)
+        lesson_project
+          .permit(*LESSON_ATTRIBUTES, :origin_identifier, :source_project_identifier, project_attributes: PROJECT_ATTRIBUTES)
+          .merge(user_id: current_user.id)
       end
 
       def lesson_projects?
@@ -63,6 +82,15 @@ def authorize_lesson_projects!
         end
       end
 
+      def authorize_source_projects!
+        return unless lesson_projects?
+
+        batch_lessons_params.each_index do |index|
+          source_project = source_project_for(index)
+          authorize! :show, source_project if source_project
+        end
+      end
+
       def authorize_blank_lesson_batch!
         authorize! :create, Lesson.new(user_id: current_user.id)
       end
diff --git a/app/controllers/api/lessons_controller.rb b/app/controllers/api/lessons_controller.rb
index 0c1385ccb..c84fcf98a 100644
--- a/app/controllers/api/lessons_controller.rb
+++ b/app/controllers/api/lessons_controller.rb
@@ -136,19 +136,5 @@ def source_project
     def source_project_identifier
       params.dig(:lesson, :source_project_identifier)
     end
-
-    def find_source_project!(identifier, locale)
-      return nil if identifier.blank?
-
-      project = ProjectLoader.new(identifier, [locale]).load
-      raise ParameterError, "source project '#{identifier}' not found" if project.nil?
-
-      # Only ExCS 'code editor' projects are remixed here; legacy scratch projects keep the stub path.
-      return nil unless project.scratch_project?
-
-      raise ParameterError, 'source project must be an Experience CS project' unless project.origin == Project::Origins::EXPERIENCE_CS
-
-      project
-    end
   end
 end
diff --git a/app/controllers/concerns/lesson_creation.rb b/app/controllers/concerns/lesson_creation.rb
index 438f461fb..f8df4ae0c 100644
--- a/app/controllers/concerns/lesson_creation.rb
+++ b/app/controllers/concerns/lesson_creation.rb
@@ -44,4 +44,18 @@ def verify_lesson_scratch!(lesson_params, source_project: nil)
   def scratch_project?(lesson_params)
     lesson_params.dig(:project_attributes, :project_type) == Project::Types::CODE_EDITOR_SCRATCH
   end
+
+  def find_source_project!(identifier, locale)
+    return nil if identifier.blank?
+
+    project = ProjectLoader.new(identifier, [locale]).load
+    raise ParameterError, "source project '#{identifier}' not found" if project.nil?
+
+    # Only ExCS 'code editor' projects are remixed here; legacy scratch projects keep the stub path.
+    return nil unless project.scratch_project?
+
+    raise ParameterError, 'source project must be an Experience CS project' unless project.origin == Project::Origins::EXPERIENCE_CS
+
+    project
+  end
 end
diff --git a/lib/concepts/lesson/operations/create_batch.rb b/lib/concepts/lesson/operations/create_batch.rb
index d1bb50f80..674d9035e 100644
--- a/lib/concepts/lesson/operations/create_batch.rb
+++ b/lib/concepts/lesson/operations/create_batch.rb
@@ -3,15 +3,18 @@
 class Lesson
   class CreateBatch
     class << self
-      def call(lessons_params:)
-        lessons_params.map { |lesson| create_one(lesson) }
+      def call(lessons_params:, source_projects: [])
+        lessons_params.zip(source_projects).map { |lesson_params, source_project| create_one(lesson_params, source_project) }
       end
 
       private
 
-      def create_one(lesson_params)
+      def create_one(lesson_params, source_project)
         origin_identifier = lesson_params[:origin_identifier]
-        Lesson::Create.call(lesson_params: lesson_params.except(:origin_identifier)).tap do |result|
+        Lesson::Create.call(
+          lesson_params: lesson_params.except(:origin_identifier, :source_project_identifier),
+          source_project:
+        ).tap do |result|
           result[:origin_identifier] = origin_identifier if origin_identifier.present?
         end
       end
diff --git a/spec/concepts/lesson/create_batch_spec.rb b/spec/concepts/lesson/create_batch_spec.rb
index ff8523aef..a73fdfdc7 100644
--- a/spec/concepts/lesson/create_batch_spec.rb
+++ b/spec/concepts/lesson/create_batch_spec.rb
@@ -58,9 +58,9 @@
 
     it 'does not pass origin_identifier to lesson creation' do
       received_params = []
-      allow(Lesson::Create).to receive(:call).and_wrap_original do |method, lesson_params:|
+      allow(Lesson::Create).to receive(:call).and_wrap_original do |method, lesson_params:, source_project: nil|
         received_params << lesson_params
-        method.call(lesson_params:)
+        method.call(lesson_params:, source_project:)
       end
 
       described_class.call(lessons_params:)
@@ -75,5 +75,24 @@
     it 'appends the origin_identifier to the second created lesson' do
       expect(result.second[:origin_identifier]).to eq('test-lesson-identifier-two')
     end
+
+    context 'when a source project is given' do
+      let!(:source_project) do
+        create(:scratch_project, user_id: nil, school_id: nil, origin: Project::Origins::EXPERIENCE_CS)
+      end
+      let(:lessons_params) do
+        super().tap { |params| params.first[:source_project_identifier] = source_project.identifier }
+      end
+      let(:source_projects) { [source_project, nil] }
+      let(:result) { described_class.call(lessons_params:, source_projects:) }
+
+      it 'builds the corresponding lesson project with the source project' do
+        expect(result.first[:lesson].project.source_project_id).to eq(source_project.id)
+      end
+
+      it 'leaves other lessons unaffected' do
+        expect(result.second[:lesson].project.source_project_id).to be_nil
+      end
+    end
   end
 end
diff --git a/spec/features/lesson/creating_a_batch_of_lessons_spec.rb b/spec/features/lesson/creating_a_batch_of_lessons_spec.rb
index bead3a881..f3123ae42 100644
--- a/spec/features/lesson/creating_a_batch_of_lessons_spec.rb
+++ b/spec/features/lesson/creating_a_batch_of_lessons_spec.rb
@@ -248,4 +248,86 @@
       expect(Lesson.count).to eq(0)
     end
   end
+
+  # #create_batch resolves each row's `source_project_identifier` through
+  # ProjectLoader, authorizes it, and hands the Project to Lesson::CreateBatch
+  # so that row's lesson project is built as a remix instead of a stub.
+  context 'when entries reference source projects' do
+    let(:source_content) { { 'targets' => [{ 'name' => 'Stage' }], 'monitors' => [], 'extensions' => [], 'meta' => {} } }
+
+    let!(:source_project) do
+      create(:scratch_project, identifier: 'my-digital-canvas', locale: 'en', user_id: nil, school_id: nil,
+                               name: 'My digital canvas', origin: Project::Origins::EXPERIENCE_CS)
+        .tap { |project| project.scratch_component.update!(content: source_content) }
+    end
+
+    let(:lesson_project_params) do
+      [
+        {
+          name: 'Lesson 1',
+          school_id: school.id,
+          source_project_identifier: source_project.identifier,
+          project_attributes: { name: 'My digital canvas', locale: 'en' }
+        },
+        {
+          name: 'Lesson 2',
+          school_id: school.id,
+          project_attributes: { name: 'Project 2', locale: 'en' }
+        }
+      ]
+    end
+
+    let(:lesson_projects_json) { JSON.parse(response.body, symbolize_names: true) }
+    let(:lesson_project_with_source) { Lesson.find(lesson_projects_json.first[:id]).project }
+    let(:stub_lesson_project) { Lesson.find(lesson_projects_json.second[:id]).project }
+
+    it 'responds 201 Created' do
+      expect(response).to have_http_status(:created)
+    end
+
+    it 'records the source project on the lesson_project_with_source' do
+      expect(lesson_project_with_source.source_project_id).to eq(source_project.id)
+    end
+
+    it 'sets the lesson_project_with_source locale to nil' do
+      expect(lesson_project_with_source.locale).to be_nil
+    end
+
+    it 'leaves source_project_identifier as nil in the stub project' do
+      expect(stub_lesson_project.source_project_id).to be_nil
+    end
+
+    context 'when the source project cannot be found' do
+      let(:lesson_project_params) do
+        [
+          {
+            name: 'Lesson 1',
+            school_id: school.id,
+            source_project_identifier: 'does-not-exist',
+            project_attributes: { name: 'My digital canvas', locale: 'en' }
+          }
+        ]
+      end
+
+      it 'responds 422 Unprocessable' do
+        expect(response).to have_http_status(:unprocessable_content)
+      end
+
+      it 'does not create any lessons' do
+        expect(Lesson.count).to eq(0)
+      end
+    end
+
+    context 'when a source_project_identifier points at a scratch project and the school does not have Scratch enabled' do
+      let(:scratch_enabled) { false }
+
+      it 'responds 403 Forbidden' do
+        expect(response).to have_http_status(:forbidden)
+      end
+
+      it 'does not create any lessons' do
+        expect(Lesson.count).to eq(0)
+      end
+    end
+  end
 end