diff --git a/lab-python-oop.ipynb b/lab-python-oop.ipynb
index c13bc58..6cd5346 100644
--- a/lab-python-oop.ipynb
+++ b/lab-python-oop.ipynb
@@ -56,21 +56,192 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 26,
    "id": "21625526-3fae-4c55-bab5-f91940070681",
    "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Creating bank accounts and performing transactions:\n",
+      "Account 1 Number: 1\n",
+      "Account 2 Number: 2\n",
+      "[Account 1] Deposited: 100. New balance: 100\n",
+      "[Account 1] Withdrew: 50. New balance: 50\n",
+      "Account 1 Balance: 50\n",
+      "[Account 2] Deposited: 200. New balance: 200\n",
+      "[Account 2] Insufficient funds. Current balance: 200, attempted withdrawal: 300\n",
+      "Account 2 Balance: 200\n"
+     ]
+    }
+   ],
+   "source": [
+    "# your code goes here\n",
+    "\n",
+    "# Version 1\n",
+    "\n",
+    "# Create a BankAccount class with the following attributes and methods:\n",
+    "# Attributes: account_number (a unique identifier for the bank account), balance (the current balance of the account. By default, is 0)\n",
+    "# Methods: deposit(amount) - adds the specified amount to the account balance, withdraw(amount) - subtracts the specified amount from the account balance,\n",
+    "# get_balance() - returns the current balance of the account, get_account_number() - returns the account number of the account\n",
+    "# Test the class by creating a few instances of BankAccount and making deposits and withdrawals.\n",
+    "# Ensure that the account_number attribute is unique for each instance of BankAccount.\n",
+    "\n",
+    "class BankAccount:\n",
+    "    account_count = 0  # Class attribute to keep track of the number of accounts\n",
+    "\n",
+    "    def __init__(self):\n",
+    "        BankAccount.account_count += 1\n",
+    "        self.account_number = BankAccount.account_count  # Unique account number\n",
+    "        self.balance = 0  # Default balance\n",
+    "\n",
+    "    def deposit(self, amount):\n",
+    "        if amount > 0:\n",
+    "            self.balance += amount\n",
+    "            print(f\"[Account {self.account_number}] Deposited: {amount}. New balance: {self.balance}\")\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Deposit amount must be positive.\")\n",
+    "\n",
+    "    def withdraw(self, amount):\n",
+    "        if amount > 0:\n",
+    "            if amount <= self.balance:\n",
+    "                self.balance -= amount\n",
+    "                print(f\"[Account {self.account_number}] Withdrew: {amount}. New balance: {self.balance}\")\n",
+    "            else:\n",
+    "                 print(\n",
+    "                    f\"[Account {self.account_number}] Insufficient funds. \"\n",
+    "                    f\"Current balance: {self.balance}, attempted withdrawal: {amount}\"\n",
+    "                )\n",
+    "\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Withdrawal amount must be positive.\")\n",
+    "\n",
+    "    def get_balance(self):\n",
+    "        return self.balance\n",
+    "\n",
+    "    def get_account_number(self):\n",
+    "        return self.account_number\n",
+    "print(\"Creating bank accounts and performing transactions:\")    \n",
+    "\n",
+    "# Test the BankAccount class\n",
+    "account1 = BankAccount()\n",
+    "account2 = BankAccount()\n",
+    "print(f\"Account 1 Number: {account1.get_account_number()}\")\n",
+    "print(f\"Account 2 Number: {account2.get_account_number()}\")\n",
+    "account1.deposit(100)\n",
+    "account1.withdraw(50)\n",
+    "print(f\"Account 1 Balance: {account1.get_balance()}\")\n",
+    "account2.deposit(200)\n",
+    "account2.withdraw(300)  # Should show insufficient funds\n",
+    "print(f\"Account 2 Balance: {account2.get_balance()}\")\n",
+    "\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "852e997f",
+   "metadata": {},
+   "source": [
+    "**Note for Version 1 (default balance = 0, no initial balance parameter):**\n",
+    ">\n",
+    "*Note:*\n",
+    ">This implementation follows the original requirement strictly: each BankAccount is created with a default balance of 0 and the account number is automatically generated using the account_count class attribute. A limitation of this version is that it does not allow setting an initial balance at instantiation, so any starting funds must be added later using deposit()."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 27,
+   "id": "0abf5db3",
+   "metadata": {},
    "outputs": [],
    "source": [
     "# your code goes here\n",
+    "\n",
+    "# Version 2\n",
+    "\n",
+    "# Create a BankAccount class with the following attributes and methods:\n",
+    "# Attributes:\n",
+    "# - account_number: a unique identifier for the bank account\n",
+    "# - balance: the current balance of the account, which can be set at initialization (default is 0)\n",
+    "#\n",
+    "# Methods:\n",
+    "# - deposit(amount): adds the specified amount to the account balance\n",
+    "# - withdraw(amount): subtracts the specified amount from the account balance if sufficient funds are available\n",
+    "# - get_balance(): returns the current balance of the account\n",
+    "# - get_account_number(): returns the account number of the account\n",
+    "#\n",
+    "# Ensure that the account_number attribute is unique for each instance of BankAccount.\n",
+    "\n",
+    "\n",
+    "\n",
+    "class BankAccount:\n",
+    "    account_count = 0\n",
+    "\n",
+    "    def __init__(self, balance=0):  # allow initial balance\n",
+    "        BankAccount.account_count += 1\n",
+    "        self.account_number = BankAccount.account_count\n",
+    "        self.balance = balance  # set initial balance\n",
+    "\n",
+    "    def deposit(self, amount):\n",
+    "        if amount > 0:\n",
+    "            self.balance += amount\n",
+    "            print(f\"[Account {self.account_number}] Deposited: {amount}. New balance: {self.balance}\")\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Deposit amount must be positive.\")\n",
+    "\n",
+    "    def withdraw(self, amount):\n",
+    "        if amount > 0:\n",
+    "            if amount <= self.balance:\n",
+    "                self.balance -= amount\n",
+    "                print(f\"[Account {self.account_number}] Withdrew: {amount}. New balance: {self.balance}\")\n",
+    "            else:\n",
+    "                print(f\"[Account {self.account_number}] Insufficient funds. Balance: {self.balance}, attempted: {amount}\")\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Withdrawal amount must be positive.\")\n",
+    "\n",
+    "    def get_balance(self):\n",
+    "        return self.balance\n",
+    "\n",
+    "    def get_account_number(self):\n",
+    "        return self.account_number\n",
+    "\n",
     "\n"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "1c97d6cc",
+   "metadata": {},
+   "source": [
+    "**Note for Version 2 (supports initial balance):**\n",
+    ">\n",
+    "*Note:*\n",
+    "> This implementation extends the original requirement by allowing an optional initial balance through __init__(self, balance=0). This makes it compatible with the lab’s provided testing code, which creates accounts with starting balances (e.g., BankAccount(1000)). The trade-off is that it slightly goes beyond the “balance is 0 by default” statement, although it still respects it (the default remains 0 when no value is passed)."
+   ]
+  },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 20,
    "id": "ee789466-d4cf-4dd8-b742-6863d42c3e5c",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Account 1 balance: 1000\n",
+      "Account 1 number: 1\n",
+      "Account 2 balance: 500\n",
+      "Account 2 number: 2\n",
+      "[Account 1] Deposited: 500. New balance: 1500\n",
+      "[Account 1] Withdrew: 200. New balance: 1300\n",
+      "Account 1 balance after transactions: 1300\n",
+      "[Account 2] Insufficient funds. Balance: 500, attempted: 600\n",
+      "Account 2 balance after transactions: 500\n"
+     ]
+    }
+   ],
    "source": [
     "# Testing the BankAccount class\n",
     "# Creating two instances of the BankAccount class with initial balances of 1000 and 500\n",
@@ -122,7 +293,29 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Create a SavingsAccount class that inherits from the BankAccount class\n",
+    "# Additional attribute:\n",
+    "# - interest_rate (annual interest rate, default is 0.01)\n",
+    "# Additional methods:\n",
+    "# - add_interest() -> adds earned interest to the balance\n",
+    "# - get_interest_rate() -> returns the interest rate\n",
+    "\n",
+    "class SavingsAccount(BankAccount):\n",
+    "\n",
+    "    def __init__(self, balance=0, interest_rate=0.01):\n",
+    "        # Initialize attributes from the parent class\n",
+    "        super().__init__(balance)\n",
+    "        self.interest_rate = interest_rate\n",
+    "\n",
+    "    def add_interest(self):\n",
+    "        interest = self.balance * self.interest_rate\n",
+    "        self.balance += interest\n",
+    "        print(f\"[Account {self.account_number}] Added interest: {interest}. New balance: {self.balance}\")\n",
+    "\n",
+    "    def get_interest_rate(self):\n",
+    "        return self.interest_rate"
    ]
   },
   {
@@ -151,12 +344,40 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 29,
    "id": "bccc7f6d-d58c-4909-9314-aaf4afc1cd30",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[Account 1] Deposited: 50. New balance: 150\n",
+      "[Account 1] Withdrew: 25. New balance: 125\n",
+      "[Account 1] Added interest: 2.5. New balance: 127.5\n",
+      "Current balance: 127.5\n",
+      "Interest rate: 0.02\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Create a SavingsAccount object with a balance of $100 and interest rate of 2%\n",
+    "savings_account = SavingsAccount(balance=100, interest_rate=0.02)\n",
+    "\n",
+    "# Deposit $50\n",
+    "savings_account.deposit(50)\n",
+    "\n",
+    "# Withdraw $25\n",
+    "savings_account.withdraw(25)\n",
+    "\n",
+    "# Add interest\n",
+    "savings_account.add_interest()\n",
+    "\n",
+    "# Print current balance and interest rate\n",
+    "print(\"Current balance:\", savings_account.get_balance())\n",
+    "print(\"Interest rate:\", savings_account.get_interest_rate())"
    ]
   },
   {
@@ -189,12 +410,63 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 30,
    "id": "3c883c6e-3cb8-4043-92d3-12409668a28e",
    "metadata": {},
    "outputs": [],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Create a CheckingAccount class that inherits from the BankAccount class.\n",
+    "# Additional attributes:\n",
+    "# - transaction_fee (fee charged per transaction, default is 1)\n",
+    "# - transaction_count (number of transactions made in the current month)\n",
+    "# Additional methods:\n",
+    "# - deduct_fees(): deducts total transaction fees and resets the transaction count\n",
+    "# - reset_transactions(): resets the transaction count to 0\n",
+    "# - get_transaction_count(): returns the current transaction count\n",
+    "# Note: deposit and withdraw methods are overwritten to track transactions.\n",
+    "\n",
+    "class CheckingAccount(BankAccount):\n",
+    "\n",
+    "    def __init__(self, balance=0, transaction_fee=1):\n",
+    "        super().__init__(balance)\n",
+    "        self.transaction_fee = transaction_fee\n",
+    "        self.transaction_count = 0\n",
+    "\n",
+    "    def deposit(self, amount):\n",
+    "        if amount > 0:\n",
+    "            self.balance += amount\n",
+    "            self.transaction_count += 1\n",
+    "            print(f\"[Account {self.account_number}] Deposited: {amount}. New balance: {self.balance}\")\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Deposit amount must be positive.\")\n",
+    "\n",
+    "    def withdraw(self, amount):\n",
+    "        if amount > 0:\n",
+    "            if amount <= self.balance:\n",
+    "                self.balance -= amount\n",
+    "                self.transaction_count += 1\n",
+    "                print(f\"[Account {self.account_number}] Withdrew: {amount}. New balance: {self.balance}\")\n",
+    "            else:\n",
+    "                print(f\"[Account {self.account_number}] Insufficient funds.\")\n",
+    "        else:\n",
+    "            print(f\"[Account {self.account_number}] Withdrawal amount must be positive.\")\n",
+    "\n",
+    "    def deduct_fees(self):\n",
+    "        total_fees = self.transaction_count * self.transaction_fee\n",
+    "        if total_fees <= self.balance:\n",
+    "            self.balance -= total_fees\n",
+    "            print(f\"Transaction fees of {total_fees}$ have been deducted from your account balance.\")\n",
+    "            self.reset_transactions()\n",
+    "        else:\n",
+    "            print(\"Insufficient balance to deduct transaction fees.\")\n",
+    "\n",
+    "    def reset_transactions(self):\n",
+    "        self.transaction_count = 0\n",
+    "\n",
+    "    def get_transaction_count(self):\n",
+    "        return self.transaction_count"
    ]
   },
   {
@@ -234,18 +506,53 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 31,
    "id": "faa5b148-c11b-4be0-b810-de8a7da81451",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[Account 2] Deposited: 100. New balance: 600\n",
+      "[Account 2] Withdrew: 50. New balance: 550\n",
+      "Transaction fees of 4$ have been deducted from your account balance.\n",
+      "Current balance: 546\n",
+      "Transaction count: 0\n",
+      "[Account 2] Deposited: 200. New balance: 746\n",
+      "[Account 2] Withdrew: 75. New balance: 671\n",
+      "Transaction fees of 4$ have been deducted from your account balance.\n",
+      "Current balance: 667\n",
+      "Transaction count: 0\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Testing the CheckingAccount class\n",
+    "\n",
+    "checking_account = CheckingAccount(balance=500, transaction_fee=2)\n",
+    "\n",
+    "checking_account.deposit(100)\n",
+    "checking_account.withdraw(50)\n",
+    "checking_account.deduct_fees()\n",
+    "\n",
+    "print(\"Current balance:\", checking_account.get_balance())\n",
+    "print(\"Transaction count:\", checking_account.get_transaction_count())\n",
+    "\n",
+    "checking_account.deposit(200)\n",
+    "checking_account.withdraw(75)\n",
+    "checking_account.deduct_fees()\n",
+    "\n",
+    "print(\"Current balance:\", checking_account.get_balance())\n",
+    "print(\"Transaction count:\", checking_account.get_transaction_count())\n"
    ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "base",
    "language": "python",
    "name": "python3"
   },
@@ -259,7 +566,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.13.5"
   }
  },
  "nbformat": 4,