diff --git a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCase.md b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCase.md
index e7923c4..a5cd482 100644
--- a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCase.md
+++ b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCase.md
@@ -31,7 +31,7 @@ System.debug(normalizedEmail); // Outputs: 'contact@example.com'
 ---
 ### Challenge: Using `toLowerCase()` for Email Deduplication
 
-You are tasked with cleaning up a set of email addresses in a Salesforce application. Due to various input methods and user errors, the set might contain emails with different case formats. Using `toLowerCase()`, you can standardize all email addresses to lowercase. 
+You are tasked with cleaning up a list of email addresses in a Salesforce application. Due to various input methods and user errors, the list might contain duplicate emails with different case formats. Using `toLowerCase()`, you can standardize all email addresses to lowercase to help identify and remove duplicates. 
 
 **Your task:**
-Write code that processes a set of email strings and converts each to lowercase.
+Write code that processes a list of email strings, converts each to lowercase, and then deduplicates the list. You will start with a predefined list of emails that includes potential duplicates with varying cases. Your method should return a set of strings. 
\ No newline at end of file
diff --git a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseSolution.cls b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseSolution.cls
index 34c0fce..abe7433 100644
--- a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseSolution.cls
+++ b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseSolution.cls
@@ -1,8 +1,9 @@
-public class ToLowerCaseSolution {
-    public Set<String> standardizeEmails(Set<String> emails) {
+public class StringUtils {
+    public Set<String> standardizeEmails(List<String> emails) {
+        Set<String> uniqueEmails = new Set<String>();
         for (String email : emails) {
-            email.toLowerCase();
+            uniqueEmails.add(email.toLowerCase());
         }
-        return emails;
+        return uniqueEmails;
     }
-}
+}
\ No newline at end of file
diff --git a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseTest.cls b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseTest.cls
index dbecaea..46d785d 100644
--- a/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseTest.cls
+++ b/force-app/main/default/apexdeepdive/string/toLowerCase/ToLowerCaseTest.cls
@@ -28,10 +28,11 @@ public with sharing class ToLowerCaseTest {
         }
 
         public TestResult test1(String testNum) {
-            Set<String> emailsInput = new Set<String>{
+            List<String> emailsInput = new List<String>{
                 'test@email.com',
                 'WarRen@cloudcodeacademy.COM',
-                'maRc@SaleFORCE.com'
+                'maRc@SaleFORCE.com',
+                'MARC@SALESFORCE.COM'
             };
             String testDesc = formatEmailSet(emailsInput);
 
@@ -45,7 +46,7 @@ public with sharing class ToLowerCaseTest {
             try {
                 Set<String> result = su.standardizeEmails(emailsInput);
                 
-                if(!emailsSolution.containsAll(result)){
+                if(result == null || !emailsSolution.containsAll(result)){
                     msg =
                     'Expected ' +
                     emailsSolution +
@@ -60,7 +61,7 @@ public with sharing class ToLowerCaseTest {
         }
 
         public TestResult test2(String testNum) {
-            Set<String> emailsInput = new Set<String>{
+            List<String> emailsInput = new List<String>{
                 'PARKER@SALESFORCE.COM',
                 'Another@emaiL.CoM',
                 '123Test@TeStER.com'
@@ -76,7 +77,7 @@ public with sharing class ToLowerCaseTest {
             try {
                 Set<String> result = su.standardizeEmails(emailsInput);
                 
-                if(!emailsSolution.containsAll(result)){
+                if(result == null || !emailsSolution.containsAll(result)){
                     msg =
                     'Expected ' +
                     emailsSolution +