diff --git a/src/main/java/com/johngrib/objects/_12_lecture/FormattedGradeLecture.java b/src/main/java/com/johngrib/objects/_12_lecture/FormattedGradeLecture.java
new file mode 100644
index 0000000..9da67e5
--- /dev/null
+++ b/src/main/java/com/johngrib/objects/_12_lecture/FormattedGradeLecture.java
@@ -0,0 +1,13 @@
+package com.johngrib.objects._12_lecture;
+
+import java.util.List;
+
+public class FormattedGradeLecture extends GradeLecture {
+  public FormattedGradeLecture(String name, int pass, List<Grade> grades, List<Integer> scores) {
+    super(name, pass, grades, scores);
+  }
+
+  public String formatAverage() {
+    return String.format("Avg: %1.1f", super.average());
+  }
+}
diff --git a/src/main/java/com/johngrib/objects/_12_lecture/Grade.java b/src/main/java/com/johngrib/objects/_12_lecture/Grade.java
new file mode 100644
index 0000000..e9f0623
--- /dev/null
+++ b/src/main/java/com/johngrib/objects/_12_lecture/Grade.java
@@ -0,0 +1,23 @@
+package com.johngrib.objects._12_lecture;
+
+import lombok.Getter;
+
+public class Grade {
+  @Getter
+  private String name;
+  private int upper, lower;
+
+  public Grade(String name, int upper, int lower) {
+    this.name = name;
+    this.upper = upper;
+    this.lower = lower;
+  }
+
+  public boolean isName(String name) {
+    return this.name.equals(name);
+  }
+
+  public boolean include(int score) {
+    return lower <= score && score <= upper;
+  }
+}
diff --git a/src/main/java/com/johngrib/objects/_12_lecture/GradeLecture.java b/src/main/java/com/johngrib/objects/_12_lecture/GradeLecture.java
new file mode 100644
index 0000000..42792e8
--- /dev/null
+++ b/src/main/java/com/johngrib/objects/_12_lecture/GradeLecture.java
@@ -0,0 +1,55 @@
+package com.johngrib.objects._12_lecture;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class GradeLecture extends Lecture {
+  private List<Grade> grades;
+
+  public GradeLecture(String title, int pass, List<Grade> grades, List<Integer> scores) {
+    super(title, pass, scores);
+    this.grades = grades;
+  }
+
+  @Override
+  public String evaluate() {
+    return super.evaluate() + ", " + gradeStatistics();
+  }
+
+  private String gradeStatistics() {
+    return grades.stream()
+            .map(grade -> format(grade))
+            .collect(Collectors.joining(" "));
+  }
+
+  private String format(Grade grade) {
+    return String.format("%s:%d", grade.getName(), gradeCount(grade));
+  }
+
+  private long gradeCount(Grade grade) {
+    return getScores().stream()
+            .filter(grade::include)
+            .count();
+  }
+
+  public double average(String gradeName) {
+    return grades.stream()
+            .filter(each -> each.isName(gradeName))
+            .findFirst()
+            .map(this::gradeAverage)
+            .orElse(0d);
+  }
+
+  private double gradeAverage(Grade grade) {
+    return getScores().stream()
+            .filter(grade::include)
+            .mapToInt(Integer::intValue)
+            .average()
+            .orElse(0);
+  }
+
+  @Override
+  public String getEvaluationMethod() {
+    return "Grade";
+  }
+}
diff --git a/src/main/java/com/johngrib/objects/_12_lecture/Lecture.java b/src/main/java/com/johngrib/objects/_12_lecture/Lecture.java
new file mode 100644
index 0000000..c55ff81
--- /dev/null
+++ b/src/main/java/com/johngrib/objects/_12_lecture/Lecture.java
@@ -0,0 +1,55 @@
+package com.johngrib.objects._12_lecture;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class Lecture {
+  /** 이수 여부를 판단할 기준 점수. */
+  private int pass;
+
+  private String title;
+  private List<Integer> scores = new ArrayList<>();
+
+  public Lecture(String title, int pass, List<Integer> scores) {
+    this.title = title;
+    this.pass = pass;
+    this.scores = scores;
+  }
+
+  /** 전체 학생들의 평균 성적을 리턴한다. */
+  public double average() {
+    return scores.stream()
+            .mapToInt(Integer::intValue)
+            .average()
+            .orElse(0);
+  }
+
+  /** 전체 학생들의 성적을 리턴한다. */
+  public List<Integer> getScores() {
+    return Collections.unmodifiableList(scores);
+  }
+
+  /** 강의를 이수한 학생의 수와 낙제한 학생의 수를 형식에 맞게 구성한 문자열을 리턴한다. */
+  public String evaluate() {
+    return String.format("Pass:%d Fail:%d", passCount(), failCount());
+  }
+
+  private long passCount() {
+    return scores.stream()
+            .filter(score -> score >= pass)
+            .count();
+  }
+
+  private long failCount() {
+    return scores.size() - passCount();
+  }
+
+  public String stats() {
+    return String.format("Title: %s, Evaluation Method: %s", title, getEvaluationMethod());
+  }
+
+  public String getEvaluationMethod() {
+    return "Pass or Fail";
+  }
+}
diff --git a/src/test/java/com/johngrib/objects/_12_lecture/GradeLectureTest.java b/src/test/java/com/johngrib/objects/_12_lecture/GradeLectureTest.java
new file mode 100644
index 0000000..583f55f
--- /dev/null
+++ b/src/test/java/com/johngrib/objects/_12_lecture/GradeLectureTest.java
@@ -0,0 +1,38 @@
+package com.johngrib.objects._12_lecture;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("GradeLecture")
+class GradeLectureTest {
+  Lecture givenLecture() {
+    return new GradeLecture(
+            "객체지향 프로그래밍",
+            70,
+            Arrays.asList(
+                    new Grade("A", 100, 95),
+                    new Grade("B", 94, 80),
+                    new Grade("C", 79, 70),
+                    new Grade("D", 69, 50),
+                    new Grade("F", 49, 0)),
+            Arrays.asList(81, 95, 75, 50, 45));
+  }
+
+  @Nested
+  @DisplayName("evaluate 메소드")
+  class Describe_evaluate {
+    @Test
+    @DisplayName("이수한 학생의 수와 낙제한 학생의 수를 표현하는 문자열을 리턴한다")
+    void it_returns_formatted_string() {
+      final String result = givenLecture().evaluate();
+
+      Assertions.assertEquals(result, "Pass:3 Fail:2, A:1 B:1 C:1 D:1 F:1");
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/com/johngrib/objects/_12_lecture/LectureTest.java b/src/test/java/com/johngrib/objects/_12_lecture/LectureTest.java
new file mode 100644
index 0000000..8c46b3c
--- /dev/null
+++ b/src/test/java/com/johngrib/objects/_12_lecture/LectureTest.java
@@ -0,0 +1,33 @@
+package com.johngrib.objects._12_lecture;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("Lecture")
+class LectureTest {
+  Lecture givenLecture() {
+    return new Lecture(
+            "객체지향 프로그래밍",
+            70,
+            Arrays.asList(81, 95, 75, 50, 45)
+    );
+  }
+
+  @Nested
+  @DisplayName("evaluate 메소드")
+  class Describe_evaluate {
+    @Test
+    @DisplayName("이수한 학생의 수와 낙제한 학생의 수를 표현하는 문자열을 리턴한다")
+    void it_returns_formatted_string() {
+      final String result = givenLecture().evaluate();
+
+      Assertions.assertEquals(result, "Pass:3 Fail:2");
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/com/johngrib/objects/_12_lecture/Professor.java b/src/test/java/com/johngrib/objects/_12_lecture/Professor.java
new file mode 100644
index 0000000..1fc12f4
--- /dev/null
+++ b/src/test/java/com/johngrib/objects/_12_lecture/Professor.java
@@ -0,0 +1,16 @@
+package com.johngrib.objects._12_lecture;
+
+public class Professor {
+  private String name;
+  private Lecture lecture;
+
+  public Professor(String name, Lecture lecture) {
+    this.name = name;
+    this.lecture = lecture;
+  }
+
+  public String compileStatistics() {
+    return String.format("[%s] %s - Avg: %.1f",
+            name, lecture.evaluate(), lecture.average());
+  }
+}
diff --git a/src/test/java/com/johngrib/objects/_12_lecture/ProfessorTest.java b/src/test/java/com/johngrib/objects/_12_lecture/ProfessorTest.java
new file mode 100644
index 0000000..7fae285
--- /dev/null
+++ b/src/test/java/com/johngrib/objects/_12_lecture/ProfessorTest.java
@@ -0,0 +1,59 @@
+package com.johngrib.objects._12_lecture;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("Professor")
+class ProfessorTest {
+
+  @Nested
+  @DisplayName("compileStatistics 메소드")
+  class Describe_compileStatistics {
+    @Nested
+    @DisplayName("다익스트라 교수의 알고리즘 Lecture 라면")
+    class Context_with_dijkstra {
+      Professor givenProfessor() {
+        return new Professor("다익스트라",
+                new Lecture("알고리즘", 70, Arrays.asList(81, 95, 75, 50, 45)));
+      }
+
+      @Test
+      @DisplayName("이수한 학생의 수, 낙제한 학생의 수, 평균을 표현하는 문자열을 리턴한다")
+      void it_returns_statistics() {
+        final String result = givenProfessor().compileStatistics();
+
+        assertEquals(result, "[다익스트라] Pass:3 Fail:2 - Avg: 69.2");
+      }
+    }
+
+    @Nested
+    @DisplayName("다익스트라 교수의 알고리즘 GradeLecture 라면")
+    class Context_with_dijkstra_grade_lecture {
+      Professor givenProfessor() {
+        return new Professor("다익스트라",
+                new GradeLecture("알고리즘", 70,
+                        Arrays.asList(
+                                new Grade("A", 100, 95),
+                                new Grade("B", 94, 80),
+                                new Grade("C", 79, 70),
+                                new Grade("D", 69, 50),
+                                new Grade("F", 49, 0)),
+                        Arrays.asList(81, 95, 75, 50, 45)));
+      }
+
+      @Test
+      @DisplayName("이수한 학생의 수, 낙제한 학생의 수, 각 학점별 수, 평균을 표현하는 문자열을 리턴한다")
+      void it_returns_statistics() {
+        final String result = givenProfessor().compileStatistics();
+
+        assertEquals(result, "[다익스트라] Pass:3 Fail:2, A:1 B:1 C:1 D:1 F:1 - Avg: 69.2");
+      }
+    }
+  }
+
+}
\ No newline at end of file