diff --git a/cs171/Lect04/bmi.py b/cs171/Lect04/bmi.py
new file mode 100644
index 0000000000000000000000000000000000000000..d336961049c36d0aabedd761c05f8f09b0de31cd
--- /dev/null
+++ b/cs171/Lect04/bmi.py
@@ -0,0 +1,39 @@
+
+
+def poundsToKg(pounds):
+    return pounds / 2.205
+
+def feetAndInchesToMeters(feet, inches):
+    totalInches = feet * 12 + inches
+    return totalInches * 0.0254
+
+# Caution: Weight in kg, height in meters
+def calculateBMI(weight, height):
+    return weight / (height * height)
+
+def getBMICategory(bmi):
+    if bmi >= 30:
+        category = "Obese"
+    elif bmi >= 25:
+        category = "Overweight"
+    elif bmi >= 18.5:
+        category = "Normal Weight"
+    else:
+        category = "Underweight"
+    return category
+
+# TODO: Add try/except and conditions to make sure users
+# enter valid values for height and weight
+
+weight = float(input("Enter weight in pounds: "))
+print("Next, you will enter you height in feet and inches, separately.")
+feet = int(input("Enter feet part of height: "))
+inches = int(input("Enter inches part of height: "))
+
+metricHeight = feetAndInchesToMeters(feet, inches)
+metricWeight = poundsToKg(weight)
+yourBMI = calculateBMI(metricWeight, metricHeight)
+
+category = getBMICategory(yourBMI)
+
+print(f"At {feet} feet and {inches} inches tall at a weight of {weight} pounds, your BMI is {yourBMI:.1f}, which is {category}.")
\ No newline at end of file
diff --git a/cs171/Lect04/hello4.py b/cs171/Lect04/hello4.py
new file mode 100644
index 0000000000000000000000000000000000000000..08e7e8a52d59389731c03795bac9b0210a0bc51c
--- /dev/null
+++ b/cs171/Lect04/hello4.py
@@ -0,0 +1,38 @@
+# print("Hello, Lecture 4")
+# 
+# print("Goodbye")
+# 
+# print(18 < 9)
+# print('C' > 'A')
+#
+
+# try:
+#     age = int(input("What's your age? "))
+# except Exception:
+#     print("That wasn't a valid age. You are now 0.")
+#     age = 0
+# 
+# if age <= 21:
+#     print("You are 21 or under.")
+# 
+# cont = input("Do you wish to continue? (y/n)")
+# 
+# print(cont == 'y')
+# 
+# 
+# if cont[0].lower() == 'y':
+#     print("Great, please continue")
+# else:
+#     print("Thanks for playing")
+#     
+#     
+# print( "&" < "(" )
+# print(ord("&"))
+# print(ord("("))
+
+letter = input("Give me a letter: ").upper()
+if letter == 'A' or letter == 'E' or letter == 'I' or letter == 'O' or letter == 'U':
+    print(f"{letter} is a vowel")
+    
+if letter in ('A', 'E', 'I', 'O', 'U'):
+    print(f"{letter.upper()} is a vowel")
diff --git a/cs171/Lect04/myGrade.py b/cs171/Lect04/myGrade.py
new file mode 100644
index 0000000000000000000000000000000000000000..74bca4addcd376c57ed362802993f5af0fd173c2
--- /dev/null
+++ b/cs171/Lect04/myGrade.py
@@ -0,0 +1,45 @@
+numberGrade = int(input("Enter numeric course grade: "))
+# 
+# if numberGrade >= 97:
+#     print("Course grade: A+")
+# elif ...
+# 
+# 
+# 
+# 
+# 
+# # Another way
+# 
+# numberGrade = int(input("Enter numeric course grade: "))
+# 
+# if numberGrade >= 97:
+#     letterGrade = "A+"
+# elif ...
+
+
+if numberGrade >= 97:
+    letterGrade = "A+"
+elif numberGrade >= 93:
+    letterGrade = "A"
+elif numberGrade >= 90:
+    letterGrade = "A-"
+elif numberGrade >= 87:
+    letterGrade = "B+"
+elif numberGrade >= 83:
+    letterGrade = "B"
+elif numberGrade >= 80:
+    letterGrade = "B-"
+elif numberGrade >= 77:
+    letterGrade = "C+"
+elif numberGrade >= 73:
+    letterGrade = "C"
+elif numberGrade >= 70:
+    letterGrade = "C-"
+elif numberGrade >= 65:
+    letterGrade = "D+"
+elif numberGrade >= 60:
+    letterGrade = "D"
+else:
+    letterGrade = "F"
+
+print(f"Your grade is {letterGrade}")
\ No newline at end of file
diff --git a/cs172/Lect04/hello.py b/cs172/Lect04/hello.py
new file mode 100644
index 0000000000000000000000000000000000000000..bcddf220f7e138bd089492a1a1e832caab18c4ca
--- /dev/null
+++ b/cs172/Lect04/hello.py
@@ -0,0 +1,76 @@
+import math
+from abc import ABC, abstractmethod
+
+class Shape(ABC):
+    
+    def __init__(self, name, color = "gray"):
+        self.__name = name
+        self.__color = color
+        
+    def getColor(self):
+        return self.__color
+    
+    def getName(self):
+        return self.__name
+ 
+    @abstractmethod
+    def getArea():
+        pass
+    
+    def __str__(self):
+        return f"A {self.__color} {self.__name}."
+    
+class Circle(Shape):
+    
+    def __init__(self, radius, color = "gray"):
+        super().__init__("Circle", color)
+        self.__radius = radius
+        
+        
+    def getRaidus(self):
+        return self.__radius
+    
+    def getPerimeter(self):
+        return 2 * self.__radius * math.pi
+    
+    def getArea(self):
+        return math.pi * (self.__radius ** 2)
+
+class Rectangle(Shape):
+    
+    def __init__(self, width, height, color = "gray"):
+        super().__init__("Rectangle", color)
+        self.__width = width
+        self.__height = height
+        
+    def getWidth(self):
+        return self.__width
+    
+    def getHeight(self):
+        return self.__height
+    
+    def getPerimeter(self):
+        return (self.__width + self.__height) * 2
+    
+    def getArea(self):
+        return self.__width * self.__height
+    
+    def __str__(self):
+        return super().__str__()[:-1] + " of area " + str(self.getArea()) + "."
+
+class Square(Shape):
+    
+    def __init__(self, side, color = "gray"):
+        super().__init__("Square", color)
+        self.__side = side
+
+    def getArea(self):
+        pass
+
+myRect = Rectangle(20, 12, "Green")
+print(myRect)
+
+myCircle = Circle(1, "Chartreuse")
+print(myCircle.getArea())
+
+mySquare = Square(10, "Purple")