diff --git a/code/module-03/m03-end/build/module03.js b/code/module-03/m03-end/build/module03.js
index 2472063..400f81a 100644
--- a/code/module-03/m03-end/build/module03.js
+++ b/code/module-03/m03-end/build/module03.js
@@ -13,7 +13,7 @@ function intOnlyLoan(loanTerms) {
     // Calculates the monthly payment of an interest only loan
     let intr = loanTerms.interestRate / 1200; // Calculates the Monthly Interest Rate of the loan
     let pmt;
-    pmt = loanTerms.principle * intr;
+    pmt = loanTerms.principal * intr;
     return 'The interest only loan payment is ' + pmt.toFixed(2);
 }
 /*  TODO: Update the convLoan function, this time replacing the three parameters with an
@@ -22,10 +22,10 @@ function convLoan(loanTerms) {
     // Calculates the monthly payment of a conventional loan
     let intr = loanTerms.interestRate / 1200; // Calculates the Monthly Interest Rate of the loan
     let pmt;
-    pmt = loanTerms.principle * intr / (1 - (Math.pow(1 / (1 + intr), loanTerms.numMonths)));
+    pmt = loanTerms.principal * intr / (1 - (Math.pow(1 / (1 + intr), loanTerms.numMonths)));
     return 'The conventional loan payment is ' + pmt.toFixed(2);
 }
-let loan1 = intOnlyLoan({ principle: 30000, interestRate: 5 });
-let loan2 = convLoan({ principle: 30000, interestRate: 5, numMonths: 180 });
+let loan1 = intOnlyLoan({ principal: 30000, interestRate: 5 });
+let loan2 = convLoan({ principal: 30000, interestRate: 5, numMonths: 180 });
 console.log(loan1); //* Returns "The interest only loan payment is 125.00" 
 console.log(loan2); //* Returns "The conventional loan payment is 237.24" 
diff --git a/code/module-03/m03-end/module03.ts b/code/module-03/m03-end/module03.ts
index 29e5214..3c31f69 100644
--- a/code/module-03/m03-end/module03.ts
+++ b/code/module-03/m03-end/module03.ts
@@ -5,7 +5,7 @@
     TODO: Declare the Loan interface. */
 
 interface Loan {
-    principle: number,
+    principal: number,
     interestRate: number    //* Interest rate percentage (eg. 14 is 14%)
 }
 
@@ -21,7 +21,7 @@ function calculateInterestOnlyLoanPayment(loanTerms: Loan): string {
     // Calculates the monthly payment of an interest only loan
     let interest: number = loanTerms.interestRate / 1200;   // Calculates the Monthly Interest Rate of the loan
     let payment: number;
-    payment = loanTerms.principle * interest;
+    payment = loanTerms.principal * interest;
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 
@@ -31,12 +31,12 @@ function calculateConventionalLoanPayment(loanTerms: ConventionalLoan): string {
     // Calculates the monthly payment of a conventional loan
     let interest: number = loanTerms.interestRate / 1200;   // Calculates the Monthly Interest Rate of the loan
     let payment: number;
-    payment = loanTerms.principle * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
+    payment = loanTerms.principal * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 
-let interestOnlyPayment = calculateInterestOnlyLoanPayment({principle: 30000, interestRate: 5});
-let conventionalPayment = calculateConventionalLoanPayment({principle: 30000, interestRate: 5, months: 180});
+let interestOnlyPayment = calculateInterestOnlyLoanPayment({principal: 30000, interestRate: 5});
+let conventionalPayment = calculateConventionalLoanPayment({principal: 30000, interestRate: 5, months: 180});
 
 console.log(interestOnlyPayment);     //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalPayment);     //* Returns "The conventional loan payment is 237.24" 
diff --git a/code/module-03/m03-start/module03.ts b/code/module-03/m03-start/module03.ts
index 5640072..cae443d 100644
--- a/code/module-03/m03-start/module03.ts
+++ b/code/module-03/m03-start/module03.ts
@@ -11,21 +11,21 @@
 
 /*  TODO: Update the calculateInterestOnlyLoanPayment function. */
 
-function calculateInterestOnlyLoanPayment(principle, interestRate) {
+function calculateInterestOnlyLoanPayment(principal, interestRate) {
     // Calculates the monthly payment of an interest only loan
     let interest = interestRate / 1200; // Calculates the Monthly Interest Rate of the loan
     let payment;
-    payment = principle * interest;
+    payment = principal * interest;
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 
 /*  TODO: Update the calculateConventionalLoanPayment function. */
 
-function calculateConventionalLoanPayment(principle, interestRate, months) {
+function calculateConventionalLoanPayment(principal, interestRate, months) {
     // Calculates the monthly payment of a conventional loan
     let interest = interestRate / 1200; // Calculates the Monthly Interest Rate of the loan
     let payment;
-    payment = principle * interest / (1 - (Math.pow(1 / (1 + interest), months)));
+    payment = principal * interest / (1 - (Math.pow(1 / (1 + interest), months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 
diff --git a/code/module-04/m04-end/build/module04.js b/code/module-04/m04-end/build/module04.js
index ffc492d..0622ec5 100644
--- a/code/module-04/m04-end/build/module04.js
+++ b/code/module-04/m04-end/build/module04.js
@@ -64,11 +64,11 @@ console.log(myArray2);
 TODO: Convert the LoanCalc function to TypeScript with strongly typed parameters, variables,
 and return types. Make the numMonths parameter optional but assign it a default value of 12
 months if omitted. */
-function LoanCalc(principle, interestRate, numMonths = 12) {
+function LoanCalc(principal, interestRate, numMonths = 12) {
     let intr = interestRate / 1200; // Calculates the monthly interest rate 
     let pmt;
     Number;
-    pmt = principle * intr / (1 - (Math.pow(1 / (1 + intr), numMonths)));
+    pmt = principal * intr / (1 - (Math.pow(1 / (1 + intr), numMonths)));
     return pmt.toFixed(2);
 }
 let myLoan = LoanCalc(1000, 5);
diff --git a/code/module-04/m04-end/module04.ts b/code/module-04/m04-end/module04.ts
index bbd0542..565f1ce 100644
--- a/code/module-04/m04-end/module04.ts
+++ b/code/module-04/m04-end/module04.ts
@@ -65,10 +65,10 @@ console.log(myArray2);
 /*  EXERCISE 2
     TODO: Update the LoanCalculator function. */
 
-function loanCalculator (principle: number, interestRate: number, months = 12): string {
+function loanCalculator (principal: number, interestRate: number, months = 12): string {
     let interest: number = interestRate / 1200;   // Calculates the monthly interest rate 
     let payment: number;
-    payment = principle * interest / (1 - (Math.pow(1/(1 + interest), months)));
+    payment = principal * interest / (1 - (Math.pow(1/(1 + interest), months)));
     return payment.toFixed(2);
 }
 
diff --git a/code/module-04/m04-start/module04.ts b/code/module-04/m04-start/module04.ts
index 00d4bfc..ea77e6a 100644
--- a/code/module-04/m04-start/module04.ts
+++ b/code/module-04/m04-start/module04.ts
@@ -62,9 +62,9 @@ let myArray2 = buildArray(8, 'descending');
 /*  EXERCISE 2
     TODO: Update the LoanCalculator function. */
 
-function loanCalculator (principle, interestRate, months) {
+function loanCalculator (principal, interestRate, months) {
     let interest = interestRate / 1200;   // Calculates the monthly interest rate
     let payment;
-    payment = principle * interest / (1 - (Math.pow(1/(1 + interest), months)));
+    payment = principal * interest / (1 - (Math.pow(1/(1 + interest), months)));
     return payment.toFixed(2);
 }
diff --git a/code/module-07/m07-end/module07_loan-programs.js b/code/module-07/m07-end/module07_loan-programs.js
index 1b05716..1abf746 100644
--- a/code/module-07/m07-end/module07_loan-programs.js
+++ b/code/module-07/m07-end/module07_loan-programs.js
@@ -4,7 +4,7 @@ exports.calculateConventionalLoanPayment = exports.calculateInterestOnlyLoanPaym
 /*  TODO Update the calculateInterestOnlyLoanPayment function. */
 function calculateInterestOnlyLoanPayment(loanTerms) {
     var payment;
-    payment = loanTerms.principle * calculateInterestRate(loanTerms.interestRate);
+    payment = loanTerms.principal * calculateInterestRate(loanTerms.interestRate);
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 exports.calculateInterestOnlyLoanPayment = calculateInterestOnlyLoanPayment;
@@ -12,7 +12,7 @@ exports.calculateInterestOnlyLoanPayment = calculateInterestOnlyLoanPayment;
 function calculateConventionalLoanPayment(loanTerms) {
     var interest = calculateInterestRate(loanTerms.interestRate);
     var payment;
-    payment = loanTerms.principle * interest / (1 - (Math.pow(1 / (1 + interest), loanTerms.months)));
+    payment = loanTerms.principal * interest / (1 - (Math.pow(1 / (1 + interest), loanTerms.months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 exports.calculateConventionalLoanPayment = calculateConventionalLoanPayment;
diff --git a/code/module-07/m07-end/module07_loan-programs.ts b/code/module-07/m07-end/module07_loan-programs.ts
index 3d11c93..bb512cd 100644
--- a/code/module-07/m07-end/module07_loan-programs.ts
+++ b/code/module-07/m07-end/module07_loan-programs.ts
@@ -4,17 +4,17 @@ import * as Loans from './module07_loans.js';
 /*  TODO Update the calculateInterestOnlyLoanPayment function. */
 export function calculateInterestOnlyLoanPayment(loanTerms: Loans.Loan): string {
     let payment: number;
-    payment = loanTerms.principle * calculateInterestRate(loanTerms.interestRate);
+    payment = loanTerms.principal * calculateInterestRate(loanTerms.interestRate);
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 /*  TODO Update the calculateConventionalLoanPayment function. */
 export function calculateConventionalLoanPayment(loanTerms: Loans.ConventionalLoan): string {
     let interest: number = calculateInterestRate(loanTerms.interestRate);
     let payment: number;
-    payment = loanTerms.principle * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
+    payment = loanTerms.principal * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 function calculateInterestRate (interestRate: number): number {
     let interest: number = interestRate / 1200;
     return interest
-}
\ No newline at end of file
+}
diff --git a/code/module-07/m07-end/module07_loans.ts b/code/module-07/m07-end/module07_loans.ts
index a0132c6..82894f5 100644
--- a/code/module-07/m07-end/module07_loans.ts
+++ b/code/module-07/m07-end/module07_loans.ts
@@ -1,8 +1,8 @@
 /*  TODO Update the interface declarations. */
 export interface Loan {
-    principle: number,
+    principal: number,
     interestRate: number        //* Interest rate percentage (eg. 14 is 14%)
 }
 export interface ConventionalLoan extends Loan {
     months: number      //* Total number of months
-}
\ No newline at end of file
+}
diff --git a/code/module-07/m07-end/module07_main.js b/code/module-07/m07-end/module07_main.js
index bce65d5..e36bd2a 100644
--- a/code/module-07/m07-end/module07_main.js
+++ b/code/module-07/m07-end/module07_main.js
@@ -5,7 +5,7 @@ exports.__esModule = true;
 /*  TODO Add the import statement. */
 var LoanPrograms = require("./module07_loan-programs.js");
 /*  TODO Update the function calls. */
-var interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({ principle: 30000, interestRate: 5 });
-var conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({ principle: 30000, interestRate: 5, months: 180 });
+var interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({ principal: 30000, interestRate: 5 });
+var conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({ principal: 30000, interestRate: 5, months: 180 });
 console.log(interestOnlyPayment); //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalLoanPayment); //* Returns "The conventional loan payment is 237.24"
diff --git a/code/module-07/m07-end/module07_main.ts b/code/module-07/m07-end/module07_main.ts
index f6d3e2b..b75be7e 100644
--- a/code/module-07/m07-end/module07_main.ts
+++ b/code/module-07/m07-end/module07_main.ts
@@ -5,7 +5,7 @@
 import * as LoanPrograms from './module07_loan-programs.js';
 
 /*  TODO Update the function calls. */
-let interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({principle: 30000, interestRate: 5});
-let conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({principle: 30000, interestRate: 5, months: 180});
+let interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({principal: 30000, interestRate: 5});
+let conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({principal: 30000, interestRate: 5, months: 180});
 console.log(interestOnlyPayment);         //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalLoanPayment);     //* Returns "The conventional loan payment is 237.24"
diff --git a/code/module-07/m07-start/module07_loan-programs.ts b/code/module-07/m07-start/module07_loan-programs.ts
index a93c75a..f36539f 100644
--- a/code/module-07/m07-start/module07_loan-programs.ts
+++ b/code/module-07/m07-start/module07_loan-programs.ts
@@ -3,17 +3,17 @@
 /*  TODO Update the calculateInterestOnlyLoanPayment function. */
 function calculateInterestOnlyLoanPayment(loanTerms: Loan): string {
     let payment: number;
-    payment = loanTerms.principle * calculateInterestRate(loanTerms.interestRate);
+    payment = loanTerms.principal * calculateInterestRate(loanTerms.interestRate);
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 /*  TODO Update the calculateConventionalLoanPayment function. */
 function calculateConventionalLoanPayment(loanTerms: ConventionalLoan): string {
     let interest: number = calculateInterestRate(loanTerms.interestRate);
     let payment: number;
-    payment = loanTerms.principle * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
+    payment = loanTerms.principal * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 function calculateInterestRate (interestRate: number): number {
     let interest: number = interestRate / 1200;
     return interest
-}
\ No newline at end of file
+}
diff --git a/code/module-07/m07-start/module07_loans.ts b/code/module-07/m07-start/module07_loans.ts
index 3e5933f..9b363ed 100644
--- a/code/module-07/m07-start/module07_loans.ts
+++ b/code/module-07/m07-start/module07_loans.ts
@@ -1,8 +1,8 @@
 /*  TODO Update the interface declarations. */
 interface Loan {
-    principle: number,
+    principal: number,
     interestRate: number        //* Interest rate percentage (eg. 14 is 14%)
 }
 interface ConventionalLoan extends Loan {
     months: number      //* Total number of months
-}
\ No newline at end of file
+}
diff --git a/code/module-07/m07-start/module07_main.ts b/code/module-07/m07-start/module07_main.ts
index 77b3fbf..56b9f73 100644
--- a/code/module-07/m07-start/module07_main.ts
+++ b/code/module-07/m07-start/module07_main.ts
@@ -4,7 +4,7 @@
 /*  TODO Add the import statement. */
 
 /*  TODO Update the function calls. */
-let interestOnlyPayment = calculateInterestOnlyLoanPayment({principle: 30000, interestRate: 5});
-let conventionalLoanPayment = calculateConventionalLoanPayment({principle: 30000, interestRate: 5, months: 180});
+let interestOnlyPayment = calculateInterestOnlyLoanPayment({principal: 30000, interestRate: 5});
+let conventionalLoanPayment = calculateConventionalLoanPayment({principal: 30000, interestRate: 5, months: 180});
 console.log(interestOnlyPayment);         //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalLoanPayment);     //* Returns "The conventional loan payment is 237.24"
diff --git a/code/module-08/m08-end/module08_loan-programs.ts b/code/module-08/m08-end/module08_loan-programs.ts
index 5aad620..ab316d1 100644
--- a/code/module-08/m08-end/module08_loan-programs.ts
+++ b/code/module-08/m08-end/module08_loan-programs.ts
@@ -4,14 +4,14 @@ namespace LoanPrograms {
     // Calculates the monthly payment of an interest only loan
     export function calculateInterestOnlyLoanPayment(loanTerms: Loans.Loan): string {
         let payment: number;
-        payment = loanTerms.principle * calculateInterestRate(loanTerms.interestRate);
+        payment = loanTerms.principal * calculateInterestRate(loanTerms.interestRate);
         return 'The interest only loan payment is ' + payment.toFixed(2);
     }
     // Calculates the monthly payment of a conventional loan      
     export function calculateConventionalLoanPayment(loanTerms: Loans.ConventionalLoan): string {
         let interest: number = calculateInterestRate(loanTerms.interestRate);
         let payment: number;
-        payment = loanTerms.principle * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
+        payment = loanTerms.principal * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
         return 'The conventional loan payment is ' + payment.toFixed(2);
     }
     function calculateInterestRate (interestRate: number): number {
diff --git a/code/module-08/m08-end/module08_loans.ts b/code/module-08/m08-end/module08_loans.ts
index 5d50e74..4ce4c5f 100644
--- a/code/module-08/m08-end/module08_loans.ts
+++ b/code/module-08/m08-end/module08_loans.ts
@@ -1,7 +1,7 @@
 
 namespace Loans {
     export interface Loan {
-        principle: number,
+        principal: number,
         interestRate: number        //* Interest rate percentage (eg. 14 is 14%)
     }
     export interface ConventionalLoan extends Loan {
diff --git a/code/module-08/m08-end/module08_main.ts b/code/module-08/m08-end/module08_main.ts
index ab0d125..1ffab16 100644
--- a/code/module-08/m08-end/module08_main.ts
+++ b/code/module-08/m08-end/module08_main.ts
@@ -10,7 +10,7 @@
 /// <reference path="module08_loan-programs.ts" />
 
 /*  TODO Update the function calls. */
-let interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({principle: 30000, interestRate: 5});
-let conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({principle: 30000, interestRate: 5, months: 180});
+let interestOnlyPayment = LoanPrograms.calculateInterestOnlyLoanPayment({principal: 30000, interestRate: 5});
+let conventionalLoanPayment = LoanPrograms.calculateConventionalLoanPayment({principal: 30000, interestRate: 5, months: 180});
 console.log(interestOnlyPayment);         //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalLoanPayment);     //* Returns "The conventional loan payment is 237.24"
diff --git a/code/module-08/m08-start/module08_main.ts b/code/module-08/m08-start/module08_main.ts
index ebd70aa..cbc775b 100644
--- a/code/module-08/m08-start/module08_main.ts
+++ b/code/module-08/m08-start/module08_main.ts
@@ -5,7 +5,7 @@
 
 
 interface Loan {
-    principle: number,
+    principal: number,
     interestRate: number        //* Interest rate percentage (eg. 14 is 14%)
 }
 interface ConventionalLoan extends Loan {
@@ -18,14 +18,14 @@ interface ConventionalLoan extends Loan {
 /*  TODO Update the calculateInterestOnlyLoanPayment function. */
 function calculateInterestOnlyLoanPayment(loanTerms: Loan): string {
     let payment: number;
-    payment = loanTerms.principle * calculateInterestRate(loanTerms.interestRate);
+    payment = loanTerms.principal * calculateInterestRate(loanTerms.interestRate);
     return 'The interest only loan payment is ' + payment.toFixed(2);
 }
 /*  TODO Update the calculateConventionalLoanPayment function. */  
 function calculateConventionalLoanPayment(loanTerms: ConventionalLoan): string {
     let interest: number = calculateInterestRate(loanTerms.interestRate);
     let payment: number;
-    payment = loanTerms.principle * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
+    payment = loanTerms.principal * interest / (1 - (Math.pow(1/(1 + interest), loanTerms.months)));
     return 'The conventional loan payment is ' + payment.toFixed(2);
 }
 function calculateInterestRate (interestRate: number): number {
@@ -37,7 +37,7 @@ function calculateInterestRate (interestRate: number): number {
 
 /*  TODO Update the function calls. */
 
-let interestOnlyPayment = calculateInterestOnlyLoanPayment({principle: 30000, interestRate: 5});
-let conventionalLoanPayment = calculateConventionalLoanPayment({principle: 30000, interestRate: 5, months: 180});
+let interestOnlyPayment = calculateInterestOnlyLoanPayment({principal: 30000, interestRate: 5});
+let conventionalLoanPayment = calculateConventionalLoanPayment({principal: 30000, interestRate: 5, months: 180});
 console.log(interestOnlyPayment);         //* Returns "The interest only loan payment is 125.00" 
 console.log(conventionalLoanPayment);     //* Returns "The conventional loan payment is 237.24"