diff --git a/src/queue/queue-data-structure.js b/src/queue/queue-data-structure.js
index 98ac0fd0..80a8b4ee 100644
--- a/src/queue/queue-data-structure.js
+++ b/src/queue/queue-data-structure.js
@@ -5,24 +5,41 @@ class Queue {
   }
 
   canEnqueue() {
-    // ... your code goes here
+    if (this.queueControl.length < this.MAX_SIZE) {
+      return true
+    } else {
+      return false
+    }
   }
 
   isEmpty() {
-    // ... your code goes here
+    if (this.queueControl.length === 0) {
+      return true
+    } else {
+      return false
+    }
   }
 
   enqueue(item) {
-    // ... your code goes here
+    if (this.canEnqueue()) {
+      this.queueControl.push(item)
+      return this.queueControl
+    } else {
+      throw new Error('QUEUE_OVERFLOW')
+    }
   }
 
   dequeue() {
-    // ... your code goes here
+    if (this.isEmpty() === false) {
+      return this.queueControl.shift()
+    } else {
+      throw new Error('QUEUE_UNDERFLOW')
+    }
   }
 
   display() {
-    // ... your code goes here
-  }  
+    return this.queueControl
+  }
 }
 
 // This is required to enable the automated tests, please ignore it.
diff --git a/src/stack/stack-data-structure.js b/src/stack/stack-data-structure.js
index 1106f6f3..bc5c6684 100644
--- a/src/stack/stack-data-structure.js
+++ b/src/stack/stack-data-structure.js
@@ -5,25 +5,43 @@ class Stack {
   }
 
   canPush() {
-    // ... your code goes here
+    if (this.stackControl.length < this.MAX_SIZE) {
+      return true
+    } else {
+      return false
+
+    }
   }
 
+
   isEmpty() {
-    // ... your code goes here
+    if (this.stackControl.length == 0) {
+      return true
+    } else {
+      return false
+    }
   }
 
   push(item) {
-    // ... your code goes here
+    if (this.canPush()) {
+      this.stackControl.push(item)
+      return this.stackControl
+    } else {
+      throw new Error('STACK_OVERFLOW')
+    }
   }
 
   pop() {
-    // ... your code goes here
+    if (this.isEmpty() === false) {
+      return this.stackControl.pop()
+    } else {
+      throw new Error('STACK_UNDERFLOW')
+    }
   }
-
   display() {
-    // ... your code goes here
-  }  
-}
+    return this.stackControl
+  }
 
+}
 // This is required to enable the automated tests, please ignore it.
 if (typeof module !== 'undefined') module.exports = Stack;