diff --git a/pom.xml b/pom.xml
index d9c0c6eb..32cc2565 100644
--- a/pom.xml
+++ b/pom.xml
@@ -7,7 +7,6 @@
     <groupId>junit-tests</groupId>
     <artifactId>tests</artifactId>
     <version>1.0-SNAPSHOT</version>
-
     <properties>
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
diff --git a/src/main/java/Cohort.java b/src/main/java/Cohort.java
new file mode 100644
index 00000000..ba9f6e49
--- /dev/null
+++ b/src/main/java/Cohort.java
@@ -0,0 +1,47 @@
+import java.util.ArrayList;
+import java.util.List;
+import java.util.LongSummaryStatistics;
+import java.util.Map;
+
+public class Cohort {
+
+    private List<Student> students;
+    private Map<Long, Student> studentMap; //New map to store students by ID
+
+    public Cohort() {
+        this.students = new ArrayList<>();
+    }
+
+    public double getCohortAverage() {
+        double avg = 0;
+        for (Student student: this.getStudents()) {
+            avg += student.getGradeAverage();
+        }
+        return avg / this.getStudents().size();
+    }
+
+    public void addStudent(Student student){
+        students.add(student);
+    }
+
+    public List<Student> getStudents() {
+        return students;
+    }
+
+    public double calculateAverage() {
+        return 0;
+    }
+
+    public <Students> Student findStudentById(long id) {
+        for (Student student : students) {
+            if (student.getId() == id) {
+                return student;
+            }
+        }
+        return null;
+    }
+
+    public Student findStudentsById(long id) {
+        return null;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/Student.java b/src/main/java/Student.java
new file mode 100644
index 00000000..67edd703
--- /dev/null
+++ b/src/main/java/Student.java
@@ -0,0 +1,63 @@
+import java.util.ArrayList;
+
+public class Student {
+
+    private long id;
+    private String name;
+    private ArrayList<Integer> grades;
+
+    public Student(long id, String name) {
+        this.id = id;
+        this.name = name;
+        this.grades = new ArrayList<>();
+    }
+
+    public long getId() {
+        return this.id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public ArrayList<Integer> getGrades() {
+        return this.grades;
+    }
+
+    public void addGrade(int grade) {
+        this.grades.add(grade);
+    }
+
+    public double getGradeAverage() {
+        if (grades.isEmpty()) {
+            return 0;
+        }
+        int sum = 0;
+        for (int grade : grades) {
+            sum += grade;
+        }
+        return(double) sum / grades.size();
+    }
+
+    public void updateGrades(int index, int newGrade) {
+        if (index >= 0 && index < grades.size()) {
+            grades.set(index, newGrade);
+        }
+    }
+    public void deleteGrades(int index) {
+        if (index >= 0 && index < grades.size()) {
+            grades.remove(index);
+        }
+    }
+
+    public void deleteGrade(int i) {
+    }
+
+    public int getGrade() {
+        return 0;
+    }
+}
+
+
+
+
diff --git a/src/test/java/CohortTest.java b/src/test/java/CohortTest.java
new file mode 100644
index 00000000..aed17b98
--- /dev/null
+++ b/src/test/java/CohortTest.java
@@ -0,0 +1,44 @@
+import org.junit.Before;
+import org.junit.Test;
+import java.util.ArrayList;
+import java.util.List;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class CohortTest {
+    private Cohort cohort;
+
+    @Before
+    public void setUp() {
+        cohort = new Cohort();
+    }
+
+    @Test
+    public void testAddStudent() {
+        Student student = new Student(80, "John Doe");
+        cohort.addStudent(student);
+        List<Student> students = cohort.getStudents();
+        assertEquals(1, students.size());
+    }
+
+    @Test
+    public void testGetStudents() {
+        Student student1 = new Student(80, "John Doe");
+        Student student2 = new Student(90, "Jane Smith");
+        cohort.addStudent(student1);
+        cohort.addStudent(student2);
+        List<Student> students = cohort.getStudents();
+        assertEquals(2, students.size());
+        assertTrue(students.contains(student1));
+        assertTrue(students.contains(student2));
+    }
+
+    @Test
+    public void testCalculateAverage() {
+        Student student1 = new Student(80, "John Doe");
+        Student student2 = new Student(90, "Jane Smith");
+        cohort.addStudent(student1);
+        cohort.addStudent(student2);
+        double average = cohort.calculateAverage();
+    }
+}
diff --git a/src/test/java/StudentTest.java b/src/test/java/StudentTest.java
new file mode 100644
index 00000000..a73773a0
--- /dev/null
+++ b/src/test/java/StudentTest.java
@@ -0,0 +1,69 @@
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class StudentTest {
+    private Student student;
+
+    @Before
+    public void setUp() {
+        student = new Student(80, "John Doe");
+    }
+
+    @Test
+    public void testGetId() {
+        assertEquals("John Doe", student.getName());
+    }
+
+    @Test
+    public void testGetName() {
+        assertEquals("John Doe", student.getName());
+    }
+
+
+    @Test
+    public void testAddGrade() {
+        student.addGrade(90);
+        student.addGrade(85);
+        student.addGrade(92);
+        ;
+
+        ArrayList<Integer> expectedGrades = new ArrayList<>();
+        expectedGrades.add(90);
+        expectedGrades.add(85);
+        expectedGrades.add(92);
+
+        assertEquals(expectedGrades, student.getGrades());
+
+    }
+
+    @Test
+    public void testGetGrades() {
+        ArrayList<Integer> grades = student.getGrades();
+        assertTrue(grades.isEmpty());
+    }
+
+    @Test
+    public void testGetGradeAverage() {
+        student.addGrade(90);
+        student.addGrade(85);
+        student.addGrade(92);
+
+    }
+
+    @Test
+
+    public void testUpdateGrade() {
+
+        student.addGrade(90);
+        student.addGrade(85);
+        student.addGrade(92);
+        int expectedGrades = 0;
+        assertEquals(expectedGrades, student.getGrade());
+    }
+}