diff --git a/checklist.md b/checklist.md
deleted file mode 100644
index 46121f865..000000000
--- a/checklist.md
+++ /dev/null
@@ -1,49 +0,0 @@
-## Common mistakes (jv-oop)
-
-#### Please don't add redundant empty lines to your code.
-We don't need them after class declaration or method signature.
-* Bad example:
-```
-public class Main {
-
-    public static void main(String[] args) {
-    
-        System.out.println("Hello world!");
-    }
-}
-```
-* Improved example:
-```
-public class Main {
-    public static void main(String[] args) {
-        System.out.println("Hello world!");
-    }
-}
-```
-
-#### Write informative messages in methods.
-Use english only and make them informative:
-message should indicate what type of `Machine` is working right now `Truck`, `Bulldozer` or `Excavator`.
-
-#### Use abstract reference instead of specific one where possible: 
-* Bad example:
-```
-Cat fluffy = new Cat();
-Dog oscar = new Dog();
-```
-This example is bad cause it won't allow us to use polymorphism in our code.
-Our reference is now bonded to specific implementation, but it is always better to depend on the abstraction.
-Let's see how we can improve it:
-* Improved example:
-```
-Animal fluffy = new Cat();
-Animal oscar = new Dog();
-```  
-
-#### Depending on the case, class elements should have different access modifiers
-Remember that if you don't use any access modifiers that will apply the default one. Do we always want
-to have all elements with default access modifiers? Remind yourself about encapsulation principle and 
-when private or public should be used.
-
-#### Write informative messages when you commit code or open a PR.         
-Bad example of commit/PR message: `done`/`fixed`/`commit`/`solution`/`added homework`/`my solution` and other one-word, abstract or random messages. 
diff --git a/src/main/java/core/basesyntax/Bulldozer.java b/src/main/java/core/basesyntax/Bulldozer.java
new file mode 100644
index 000000000..ee9b58f09
--- /dev/null
+++ b/src/main/java/core/basesyntax/Bulldozer.java
@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Bulldozer extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Trzasku-Trzask");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("The Bulldozer stopped working");
+    }
+}
diff --git a/src/main/java/core/basesyntax/Excavator.java b/src/main/java/core/basesyntax/Excavator.java
new file mode 100644
index 000000000..67060173f
--- /dev/null
+++ b/src/main/java/core/basesyntax/Excavator.java
@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Excavator extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Kopu-Kop");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("The Excavator stopped working");
+    }
+}
diff --git a/src/main/java/core/basesyntax/Machine.java b/src/main/java/core/basesyntax/Machine.java
new file mode 100644
index 000000000..4219699a5
--- /dev/null
+++ b/src/main/java/core/basesyntax/Machine.java
@@ -0,0 +1,7 @@
+package core.basesyntax;
+
+public abstract class Machine {
+    public abstract void doWork();
+
+    public abstract void stopWork();
+}
diff --git a/src/main/java/core/basesyntax/MainApp.java b/src/main/java/core/basesyntax/MainApp.java
index f99e9a019..88e6ee7b8 100644
--- a/src/main/java/core/basesyntax/MainApp.java
+++ b/src/main/java/core/basesyntax/MainApp.java
@@ -1,5 +1,15 @@
 package core.basesyntax;
 
 public class MainApp {
+    public static void main(String[] args) {
+        Machine[] machines = {new Bulldozer(), new Excavator(), new Truck()};
+        printMethodsInLoop(machines);
+    }
 
+    public static void printMethodsInLoop(Machine[] machines) {
+        for (Machine machine : machines) {
+            machine.doWork();
+            machine.stopWork();
+        }
+    }
 }
diff --git a/src/main/java/core/basesyntax/Truck.java b/src/main/java/core/basesyntax/Truck.java
new file mode 100644
index 000000000..5d0ee1284
--- /dev/null
+++ b/src/main/java/core/basesyntax/Truck.java
@@ -0,0 +1,13 @@
+package core.basesyntax;
+
+public class Truck extends Machine {
+    @Override
+    public void doWork() {
+        System.out.println("Brum-Brum");
+    }
+
+    @Override
+    public void stopWork() {
+        System.out.println("The Truck stopped working");
+    }
+}