diff --git a/DomainModel.md b/DomainModel.md
new file mode 100644
index 0000000..61838cc
--- /dev/null
+++ b/DomainModel.md
@@ -0,0 +1,29 @@
+# Domain Model
+
+## CohortManager Class
+
+| Method  | Variables  | Scenario  | Output  |
+|---|---|---|---|
+|   | ArrayList\<String> cohorts |   |   |
+| search(String name)  |   | Found name in cohorts  | return true  |
+|   |   | Did not find name in cohorts  | return false  |
+
+## ShoppingCart Class
+
+| Method  | Variables  | Scenario  | Output  |
+|---|---|---|---|
+|   | ArrayList\<ShopItem> cart |   |   |
+| getTotalCost()  |   | valid total cost  | return total cost of items in basket  |
+|   |   | invalid total cost  | return -1  |
+| getReceipt()  |   | valid list of items  | return receipt String  |
+|   |   | invalid list of items  | return null  |
+| addItem(ShopItem item)  |   | valid item  | add item to cart  |
+|   |   | invalid item  | throw error|
+
+## ShopItem Class
+| Method  | Variables  | Scenario  | Output  |
+|---|---|---|---|
+|   | String name  |   |   |
+|   | Float price  |   |   |
+| getPrice()  |   |   | return price  |
+
diff --git a/src/main/java/com/booleanuk/core/Basket.java b/src/main/java/com/booleanuk/core/Basket.java
new file mode 100644
index 0000000..92d19a3
--- /dev/null
+++ b/src/main/java/com/booleanuk/core/Basket.java
@@ -0,0 +1,29 @@
+package com.booleanuk.core;
+
+import java.util.HashMap;
+
+public class Basket {
+    private HashMap<String, Integer> items;
+
+    public Basket() {
+        items = new HashMap<>();
+    }
+
+    boolean add(String product, int price) {
+        if (items.containsKey(product))
+            return false;
+
+        items.put(product, price);
+        return true;
+    }
+
+    int total() {
+        int total = 0;
+
+        for (Integer price : items.values()) {
+            total += price;
+        }
+
+        return total;
+    }
+}
diff --git a/src/main/java/com/booleanuk/core/CohortManager.java b/src/main/java/com/booleanuk/core/CohortManager.java
index 48a1b26..675a2f0 100644
--- a/src/main/java/com/booleanuk/core/CohortManager.java
+++ b/src/main/java/com/booleanuk/core/CohortManager.java
@@ -1,5 +1,15 @@
 package com.booleanuk.core;
 
+import java.util.ArrayList;
+
 public class CohortManager {
+    private ArrayList<String> cohorts;
+
+    public CohortManager(ArrayList<String> cohorts) {
+        this.cohorts = cohorts;
+    }
 
-}
+    boolean search(String name) {
+        return cohorts.contains(name);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/com/booleanuk/core/BasketTest.java b/src/test/java/com/booleanuk/core/BasketTest.java
new file mode 100644
index 0000000..bb0406b
--- /dev/null
+++ b/src/test/java/com/booleanuk/core/BasketTest.java
@@ -0,0 +1,44 @@
+package com.booleanuk.core;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class BasketTest {
+    @Test    
+    void testAddNonExistingItem() {
+        Basket basket = new Basket();
+        String itemName = "orange";
+        int price = 5;
+
+        Assertions.assertTrue(basket.add(itemName, price));
+    }
+
+    @Test    
+    void testAddExistingItem() {
+        Basket basket = new Basket();
+        String itemName = "orange";
+        int price = 5;
+
+        basket.add(itemName, price);
+        
+        Assertions.assertFalse(basket.add(itemName, price));
+    }
+
+    @Test
+    void testTotalEmptyBasket() {
+        Basket basket = new Basket();
+
+        Assertions.assertEquals(0, basket.total());
+    }
+
+    @Test
+    void testTotal() {
+        Basket basket = new Basket();
+        basket.add("a", 5);
+        basket.add("b",35);
+        basket.add("c", 100);
+        basket.add("d", 70);
+
+        Assertions.assertEquals(210, basket.total());
+    }
+}
diff --git a/src/test/java/com/booleanuk/core/CohortManagerTest.java b/src/test/java/com/booleanuk/core/CohortManagerTest.java
index 5dea868..8d6094e 100644
--- a/src/test/java/com/booleanuk/core/CohortManagerTest.java
+++ b/src/test/java/com/booleanuk/core/CohortManagerTest.java
@@ -1,8 +1,42 @@
 package com.booleanuk.core;
 
+import java.util.ArrayList;
+
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 class CohortManagerTest {
+    @Test
+    public void searchForCohortThatExists() {
+        // setup
+        ArrayList<String> cohorts = new ArrayList<>(){{
+            add("Robin");
+            add("Mathias");
+            add("Magnus");
+            add("Jonas");
+            add("Thomas");
+        }};
+        CohortManager manager = new CohortManager(cohorts);
+        String name = "Robin";
+
+        // execute and verify
+        Assertions.assertTrue(manager.search(name));
+    }
+
+    @Test
+    public void searchForCohortThatDoesNotExist() {
+        // setup
+        ArrayList<String> cohorts = new ArrayList<>(){{
+            add("Robin");
+            add("Mathias");
+            add("Magnus");
+            add("Jonas");
+            add("Thomas");
+        }};
+        CohortManager manager = new CohortManager(cohorts);
+        String name = "Andreas";
 
+        // execute and verify
+        Assertions.assertFalse(manager.search(name));
+    }
 }