diff --git a/app/models/series.rb b/app/models/series.rb
index 1d6bbab1..b50a38ee 100644
--- a/app/models/series.rb
+++ b/app/models/series.rb
@@ -33,10 +33,6 @@ class Series
         start_date: start_date,
         end_date: end_date,
         interval: interval,
-        trend: Trend.new(
-          current: ordered.last[:value],
-          previous: ordered.first[:value]
-        ),
         values: [ nil, *ordered ].each_cons(2).map do |prev_value, curr_value|
           Value.new(
             date: curr_value[:date],
diff --git a/test/controllers/onboardings_controller_test.rb b/test/controllers/onboardings_controller_test.rb
new file mode 100644
index 00000000..129aaecf
--- /dev/null
+++ b/test/controllers/onboardings_controller_test.rb
@@ -0,0 +1,167 @@
+require "test_helper"
+
+class OnboardingsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    @user = users(:family_admin)
+    @family = @user.family
+
+    # Reset onboarding state
+    @user.update!(set_onboarding_preferences_at: nil)
+
+    sign_in @user
+  end
+
+  test "should get show" do
+    get onboarding_url
+    assert_response :success
+    assert_select "h1", text: /set up your account/i
+  end
+
+  test "should get preferences" do
+    get preferences_onboarding_url
+    assert_response :success
+    assert_select "h1", text: /preferences/i
+  end
+
+  test "preferences page renders Series chart data without errors" do
+    get preferences_onboarding_url
+    assert_response :success
+
+    # This test specifically targets the Series model bug
+    # The page should render without throwing the "unknown keyword: :trend" error
+    assert_select "[data-controller='time-series-chart']"
+    assert_select "#previewChart"
+
+    # Verify that the Series.from_raw_values call in the view works
+    # If the Series bug existed, this would raise an ActionView::Template::Error
+    assert_no_match /unknown keyword: :trend/, response.body
+  end
+
+  test "preferences page includes chart with valid JSON data" do
+    get preferences_onboarding_url
+    assert_response :success
+
+    # Extract the chart data from the response
+    chart_data_match = response.body.match(/data-time-series-chart-data-value="([^"]*)"/)
+    assert chart_data_match, "Chart data attribute should be present"
+
+    # Decode HTML entities and parse JSON
+    chart_data_json = CGI.unescapeHTML(chart_data_match[1])
+
+    # Should be valid JSON
+    assert_nothing_raised do
+      chart_data = JSON.parse(chart_data_json)
+
+      # Verify expected structure
+      assert chart_data.key?("start_date")
+      assert chart_data.key?("end_date")
+      assert chart_data.key?("interval")
+      assert chart_data.key?("trend")
+      assert chart_data.key?("values")
+
+      # Verify trend has expected structure
+      trend = chart_data["trend"]
+      assert trend.key?("value")
+      assert trend.key?("percent")
+      assert trend.key?("current")
+      assert trend.key?("previous")
+
+      # Verify values array has expected structure
+      values = chart_data["values"]
+      assert values.is_a?(Array)
+      assert values.length > 0
+
+      values.each do |value|
+        assert value.key?("date")
+        assert value.key?("value")
+        assert value.key?("trend")
+      end
+    end
+  end
+
+  test "should get goals" do
+    get goals_onboarding_url
+    assert_response :success
+    assert_select "h1", text: /What brings you to Maybe/i
+  end
+
+  test "should get trial" do
+    get trial_onboarding_url
+    assert_response :success
+  end
+
+  test "preferences page shows currency formatting example" do
+    get preferences_onboarding_url
+    assert_response :success
+
+    # Should show formatted currency example
+    assert_select "p", text: /\$2,325\.25/
+    assert_select "span", text: /\+\$78\.90/
+  end
+
+  test "preferences page shows date formatting example" do
+  get preferences_onboarding_url
+  assert_response :success
+
+  # Should show formatted date example (checking for the specific format shown)
+  assert_match /10-23-2024/, response.body
+end
+
+  test "preferences page includes all required form fields" do
+  get preferences_onboarding_url
+  assert_response :success
+
+  # Verify all form fields are present
+  assert_select "select[name='user[family_attributes][locale]']"
+  assert_select "select[name='user[family_attributes][currency]']"
+  assert_select "select[name='user[family_attributes][date_format]']"
+  assert_select "select[name='user[theme]']"
+  assert_select "button[type='submit']"
+end
+
+  test "preferences page includes JavaScript controllers" do
+    get preferences_onboarding_url
+    assert_response :success
+
+    # Should include onboarding controller for dynamic updates
+    assert_select "[data-controller*='onboarding']"
+    assert_select "[data-controller*='time-series-chart']"
+  end
+
+  test "all onboarding pages set correct layout" do
+    # Test that all onboarding pages use the wizard layout
+    get onboarding_url
+    assert_response :success
+
+    get preferences_onboarding_url
+    assert_response :success
+
+    get goals_onboarding_url
+    assert_response :success
+
+    get trial_onboarding_url
+    assert_response :success
+  end
+
+  test "onboarding pages require authentication" do
+  sign_out
+
+  get onboarding_url
+  assert_redirected_to new_session_url
+
+  get preferences_onboarding_url
+  assert_redirected_to new_session_url
+
+  get goals_onboarding_url
+  assert_redirected_to new_session_url
+
+  get trial_onboarding_url
+  assert_redirected_to new_session_url
+end
+
+    private
+
+      def sign_out
+        delete session_path(@user.sessions.last) if @user.sessions.any?
+end
+end
diff --git a/test/system/onboardings_test.rb b/test/system/onboardings_test.rb
new file mode 100644
index 00000000..dd1c93c9
--- /dev/null
+++ b/test/system/onboardings_test.rb
@@ -0,0 +1,192 @@
+require "application_system_test_case"
+
+class OnboardingsTest < ApplicationSystemTestCase
+  setup do
+    @user = users(:family_admin)
+    @family = @user.family
+
+    # Reset onboarding state
+    @user.update!(set_onboarding_preferences_at: nil)
+
+    sign_in @user
+  end
+
+  test "can complete the full onboarding flow" do
+    # Start at the main onboarding page
+    visit onboarding_path
+
+    assert_text "Let's set up your account"
+    assert_button "Get started"
+
+    # Navigate to preferences
+    click_button "Get started"
+
+    assert_current_path preferences_onboarding_path
+    assert_text "Set your preferences"
+
+    # Test that the chart renders without errors (this would catch the Series bug)
+    assert_selector "[data-controller='time-series-chart']"
+
+    # Fill out preferences form
+    select "English", from: "user_family_attributes_locale"
+    select "United States Dollar (USD)", from: "user_family_attributes_currency"
+    select "MM/DD/YYYY", from: "user_family_attributes_date_format"
+    select "Light", from: "user_theme"
+
+    # Submit preferences
+    click_button "Continue"
+
+    # Should redirect to goals page
+    assert_current_path goals_onboarding_path
+    assert_text "What brings you to Maybe?"
+  end
+
+  test "preferences page renders chart without errors" do
+    visit preferences_onboarding_path
+
+    # This test specifically targets the Series model bug
+    # The chart should render without throwing JavaScript errors
+    assert_selector "[data-controller='time-series-chart']"
+    assert_selector "#previewChart"
+
+    # Verify the chart data is properly formatted JSON
+    chart_element = find("[data-controller='time-series-chart']")
+    chart_data = chart_element["data-time-series-chart-data-value"]
+
+    # Should be valid JSON
+    assert_nothing_raised do
+      JSON.parse(chart_data)
+    end
+
+    # Verify the preview example shows
+    assert_text "Example"
+    assert_text "$2,325.25"
+    assert_text "+$78.90"
+  end
+
+  test "can change currency and see preview update" do
+    visit preferences_onboarding_path
+
+    # Change currency
+    select "Euro (EUR)", from: "user_family_attributes_currency"
+
+    # The preview should update (this tests the JavaScript controller)
+    # Note: This would require the onboarding controller to handle currency changes
+    assert_text "Example"
+  end
+
+  test "can change date format and see preview update" do
+    visit preferences_onboarding_path
+
+    # Change date format
+    select "DD/MM/YYYY", from: "user_family_attributes_date_format"
+
+    # The preview should update
+    assert_text "Example"
+  end
+
+  test "can change theme" do
+    visit preferences_onboarding_path
+
+    # Change theme
+    select "Dark", from: "user_theme"
+
+    # Theme should be applied (this tests the JavaScript controller)
+    assert_text "Example"
+  end
+
+  test "preferences form validation" do
+    visit preferences_onboarding_path
+
+    # Clear required fields and try to submit
+    select "", from: "user_family_attributes_locale"
+    click_button "Continue"
+
+    # Should stay on preferences page with validation errors
+    assert_current_path preferences_onboarding_path
+  end
+
+  test "preferences form saves data correctly" do
+    visit preferences_onboarding_path
+
+    # Fill out form with specific values
+    select "Spanish", from: "user_family_attributes_locale"
+    select "Euro (EUR)", from: "user_family_attributes_currency"
+    select "DD/MM/YYYY", from: "user_family_attributes_date_format"
+    select "Dark", from: "user_theme"
+
+    click_button "Continue"
+
+    # Verify data was saved
+    @family.reload
+    @user.reload
+
+    assert_equal "es", @family.locale
+    assert_equal "EUR", @family.currency
+    assert_equal "DD/MM/YYYY", @family.date_format
+    assert_equal "dark", @user.theme
+    assert_not_nil @user.set_onboarding_preferences_at
+  end
+
+  test "goals page renders correctly" do
+    # Complete preferences first
+    @user.update!(set_onboarding_preferences_at: Time.current)
+
+    visit goals_onboarding_path
+
+    assert_text "What brings you to Maybe?"
+    assert_button "Continue"
+  end
+
+  test "trial page renders correctly" do
+    visit trial_onboarding_path
+
+    assert_text "trial" # Adjust based on actual content
+  end
+
+  test "navigation between onboarding steps" do
+    # Start at main onboarding
+    visit onboarding_path
+    click_button "Get started"
+
+    # Should be at preferences
+    assert_current_path preferences_onboarding_path
+
+    # Complete preferences
+    select "English", from: "user_family_attributes_locale"
+    select "United States Dollar (USD)", from: "user_family_attributes_currency"
+    select "MM/DD/YYYY", from: "user_family_attributes_date_format"
+    click_button "Continue"
+
+    # Should be at goals
+    assert_current_path goals_onboarding_path
+  end
+
+  test "onboarding nav shows correct steps" do
+    visit preferences_onboarding_path
+
+    # Check that navigation shows current step
+    assert_selector ".onboarding-nav" # Adjust selector based on actual implementation
+  end
+
+  test "logout option is available during onboarding" do
+    visit preferences_onboarding_path
+
+    # Should have logout option
+    assert_link "Sign out" # Adjust based on actual implementation
+  end
+
+  private
+
+    def sign_in(user)
+      visit new_session_path
+      within "form" do
+        fill_in "Email", with: user.email
+        fill_in "Password", with: user_password_test
+        click_on "Log in"
+      end
+
+      # Wait for successful login
+      assert_current_path root_path
+end
+end