diff --git a/.github/workflows/run_test.yml b/.github/workflows/run_test.yml
new file mode 100644
index 00000000..c45bcbfc
--- /dev/null
+++ b/.github/workflows/run_test.yml
@@ -0,0 +1,32 @@
+name: simple_calculator unit test
+  
+on: [push]  
+  
+jobs:  
+  build:  
+    runs-on: ubuntu-latest  
+    strategy:  
+      matrix:  
+        python-version: ["3.10"]  
+  
+    steps:  
+      - uses: actions/checkout@v3  
+      - name: Set up Python ${{ matrix.python-version }}  
+        uses: actions/setup-python@v4  
+        with:  
+          python-version: ${{ matrix.python-version }}  
+      - name: Install dependencies  
+        run: |  
+          python -m pip install --upgrade pip  
+          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi  
+      - name: Lint with Ruff  
+        run: |  
+          pip install ruff  
+          ruff --format=github --target-version=py310 .  
+        continue-on-error: true  
+      - name: Test with pytest  
+        run: |  
+          coverage run -m pytest tests/tests_1b.py -v -s  
+      - name: Generate Coverage Report  
+        run: |  
+          coverage report -m
\ No newline at end of file
diff --git a/labs/lab_1/lab_1a.py b/labs/lab_1/lab_1a.py
index 9d15ec83..3df380f3 100644
--- a/labs/lab_1/lab_1a.py
+++ b/labs/lab_1/lab_1a.py
@@ -3,14 +3,16 @@
 
 The first lab in the BWSI CSS course. To complete this lab, fill out the variable on line 10
 with your name. Then, save the code, add it to the staging area, and commit it to the Git tree.
+This is to simulate a change made on a robot: robot_speed = 5 # m/s
 """
 
 def main():
     print("Hello World!")
 
-    name = "" # TODO: Insert your name between the double quotes
+    name = "Om Durukkar" # TODO: Insert your name between the double quotes
 
     print(f"{name}, Welcome to the CSS course!")
+    print("Hello all! My name is Om. I like STEM. My favorite subjects outside and inside of school are calculus, chemistry, computer science (particularly machine learning). I program competitively. I also cook food. I like to camp and enjoy the outdoors with my Scout troop.")
 
 if __name__ == "__main__":
     main()
diff --git a/labs/lab_1/lab_1b.py b/labs/lab_1/lab_1b.py
index e58dd957..7df756a4 100644
--- a/labs/lab_1/lab_1b.py
+++ b/labs/lab_1/lab_1b.py
@@ -36,14 +36,31 @@ def simple_calculator(operation: str, num1: float, num2: float) -> float:
             raise ValueError("Cannot divide by zero.")
     else:
         raise ValueError("Invalid operation. Please choose from 'add', 'subtract', 'multiply', or 'divide'.")
+    
+def input_number(prompt: str) -> float:
+    """
+    Helper function to request a number from the user and ensure it's a valid float.
+
+    Args:
+        prompt (str): The prompt to display to the user.
+
+    Returns:
+        float: The sanitized number input by the user.
+    """
+    while True:
+        try:
+            number = float(input(prompt))
+            return number
+        except ValueError:
+             print("Invalid input. Please enter a valid number.")
 
 def main():
     
     print(f"===== Simple Calculator =====")
 
     # Ask the user for sample input    
-    num1 = float(input("Enter the first number: "))
-    num2 = float(input("Enter the second number: "))
+    num1 = input_number("Enter the first number: ")
+    num2 = input_number("Enter the second number: ")
     operation = input("Enter the operation (add, subtract, multiply, divide): ").strip().lower()
 
     # Perform the calculation and display the result
diff --git a/labs/lab_1/lab_1c.py b/labs/lab_1/lab_1c.py
index 40cf98db..baa500db 100644
--- a/labs/lab_1/lab_1c.py
+++ b/labs/lab_1/lab_1c.py
@@ -7,8 +7,6 @@
 
 Derived from LeetCode problem: https://leetcode.com/problems/maximum-subarray/ (leetcode medium)
 """
-
-# TODO: Find and resolve the bug in the following implementation. Create unit tests to verify your fix.
 def max_subarray_sum(nums: list[int]) -> int:
     """
     Function that takes in a list of integers and returns the maximum sum of any contiguous subarray.
@@ -20,11 +18,14 @@ def max_subarray_sum(nums: list[int]) -> int:
         int: The maximum sum of any contiguous subarray.
     """
 
+    if not nums:
+        raise ValueError("Input list must contain at least one number.")
+
     max_current = max_global = nums[0]
     
-    for num in nums:
+    for num in nums[1:]:
         max_current = max(num, max_current + num)
-        if max_current < max_global:
+        if max_current > max_global:
             max_global = max_current
             
     return max_global
@@ -36,4 +37,4 @@ def main():
     print(f"Maximum subarray sum: {result}")
 
 if __name__ == "__main__":
-    main()
\ No newline at end of file
+    main()
diff --git a/tests/test_lab_1c.py b/tests/test_lab_1c.py
new file mode 100644
index 00000000..ca24cbfa
--- /dev/null
+++ b/tests/test_lab_1c.py
@@ -0,0 +1,38 @@
+"""
+Unit tests for max_subarray_sum in labs.lab_1.lab_1c.
+"""
+
+import pytest
+
+from labs.lab_1.lab_1c import max_subarray_sum
+
+
+def test_example_from_prompt():
+    # Typical mix of positives and negatives
+    assert max_subarray_sum([-2, 1, -3, 4, -1, 2, 1, -5, 4]) == 6  # [4, -1, 2, 1]
+
+
+def test_all_negative_returns_least_negative():
+    assert max_subarray_sum([-8, -3, -6, -2, -5, -4]) == -2
+
+
+def test_single_element_list():
+    assert max_subarray_sum([7]) == 7
+
+
+def test_all_positive_accumulates_entire_list():
+    assert max_subarray_sum([1, 2, 3, 4]) == 10
+
+
+def test_empty_list_raises_value_error():
+    with pytest.raises(ValueError, match="Input list must contain at least one number."):
+        max_subarray_sum([])
+
+
+def test_prefix_negative_suffix_positive():
+    # Ensures algorithm resets after negative prefix
+    assert max_subarray_sum([-10, 5, 6]) == 11
+
+
+if __name__ == "__main__":
+    pytest.main()
diff --git a/tests/tests_1b.py b/tests/tests_1b.py
index be6b822d..30c19c25 100644
--- a/tests/tests_1b.py
+++ b/tests/tests_1b.py
@@ -11,11 +11,13 @@ def test_addition():
     assert simple_calculator("add", 5, 3) == 8          # Test for positive numbers
     assert simple_calculator("add", -2, 2) == 0         # Test for negative and positive number
     assert simple_calculator("add", 0, 0) == 0          # Test for zero addition
+    assert simple_calculator("add", -2, -4) == -6       # Test for negative numbers
 
 def test_subtraction():
     assert simple_calculator("subtract", 5, 3) == 2     # Test for positive numbers
     assert simple_calculator("subtract", -2, -2) == 0   # Test for negative numbers
     assert simple_calculator("subtract", 0, 5) == -5    # Test for zero minuend
+    assert simple_calculator("subtract", 0, -5) == 5 
 
 def test_multiplication():
     assert simple_calculator("multiply", 5, 3) == 15    # Test for positive numbers