diff --git a/Week1/practice-exercises/1-remove-the-comma.js b/Week1/practice-exercises/1-remove-the-comma.js
index b71cffd..002f52c 100644
--- a/Week1/practice-exercises/1-remove-the-comma.js
+++ b/Week1/practice-exercises/1-remove-the-comma.js
@@ -7,8 +7,12 @@
 
 let myString = 'hello,this,is,a,difficult,to,read,sentence';
 
+// ✅ Replace commas with spaces
+myString = myString.replace(/,/g, ' ');
 
+// Optional: log it
+console.log(myString);
 
 /* --- Code that will test your solution, do NOT change. Write above this line --- */
 
-console.assert(myString === 'hello this is a difficult to read sentence', 'There is something wrong with your solution');
\ No newline at end of file
+console.assert(myString === 'hello this is a difficult to read sentence', 'There is something wrong with your solution');
diff --git a/Week1/practice-exercises/2-even-odd-reporter.js b/Week1/practice-exercises/2-even-odd-reporter.js
index 6edf23e..9273364 100644
--- a/Week1/practice-exercises/2-even-odd-reporter.js
+++ b/Week1/practice-exercises/2-even-odd-reporter.js
@@ -7,3 +7,10 @@
  *  If it's even, log to the console The number [PUT_NUMBER_HERE] is even!.
  */
 
+for (let i = 0; i <= 20; i++) {
+  if (i % 2 === 0) {
+    console.log(`The number ${i} is even!`);
+  } else {
+    console.log(`The number ${i} is odd!`);
+  }
+}
diff --git a/Week1/practice-exercises/3-recipe-card.js b/Week1/practice-exercises/3-recipe-card.js
index 24bcb54..7326538 100644
--- a/Week1/practice-exercises/3-recipe-card.js
+++ b/Week1/practice-exercises/3-recipe-card.js
@@ -4,11 +4,21 @@
  *   Declare a variable that holds an empty object literal (your meal recipe).
  *   Give the object 3 properties: a title (string), a servings (number) and an ingredients (array of strings) property.
  *   Log each property out separately, using a loop (for, while or do/while)
- *   
- * Expected result:
- *   
- *   Meal name: Omelette
- *   Serves: 2
- *   Ingredients: 4 eggs, 2 strips of bacon, 1 tsp salt/pepper
  */
 
+
+const recipe = {
+  title: 'Omelette',
+  servings: 2,
+  ingredients: ['4 eggs', '2 strips of bacon', '1 tsp salt/pepper'],
+};
+
+// Log title and servings
+console.log(`Meal name: ${recipe.title}`);
+console.log(`Serves: ${recipe.servings}`);
+
+// Log ingredients using a loop
+console.log('Ingredients:');
+for (let i = 0; i < recipe.ingredients.length; i++) {
+  console.log(`- ${recipe.ingredients[i]}`);
+}
diff --git a/Week1/practice-exercises/4-reading-list.js b/Week1/practice-exercises/4-reading-list.js
index f535657..66da3cb 100644
--- a/Week1/practice-exercises/4-reading-list.js
+++ b/Week1/practice-exercises/4-reading-list.js
@@ -9,3 +9,31 @@
  *  If you haven't read it log a string like You still need to read "The Lord of the Rings"
  */
 
+const books = [
+  {
+    title: 'The Hobbit',
+    author: 'J.R.R. Tolkien',
+    alreadyRead: true,
+  },
+  {
+    title: 'The Lord of the Rings',
+    author: 'J.R.R. Tolkien',
+    alreadyRead: false,
+  },
+  {
+    title: 'Harry Potter and the Sorcerer\'s Stone',
+    author: 'J.K. Rowling',
+    alreadyRead: true,
+  },
+];
+
+for (let i = 0; i < books.length; i++) {
+  const book = books[i];
+  console.log(`${book.title} by ${book.author}`);
+  
+  if (book.alreadyRead) {
+    console.log(`You already read "${book.title}"`);
+  } else {
+    console.log(`You still need to read "${book.title}"`);
+  }
+}
diff --git a/Week1/practice-exercises/5-who-wants-a-drink.js b/Week1/practice-exercises/5-who-wants-a-drink.js
index f37f02b..e20f152 100644
--- a/Week1/practice-exercises/5-who-wants-a-drink.js
+++ b/Week1/practice-exercises/5-who-wants-a-drink.js
@@ -8,4 +8,24 @@
  */
 
 // There are 3 different types of drinks:
-const drinkTypes = ['cola', 'lemonade', 'water'];
\ No newline at end of file
+const drinkTypes = ['cola', 'lemonade', 'water'];
+const drinkTray = [];
+
+const drinkCounts = {
+  cola: 0,
+  lemonade: 0,
+  water: 0,
+};
+
+for (let i = 0; i < 5; i++) {
+  for (let j = 0; j < drinkTypes.length; j++) {
+    const drink = drinkTypes[j];
+    if (drinkCounts[drink] < 2) {
+      drinkTray.push(drink);
+      drinkCounts[drink]++;
+      break;
+    }
+  }
+}
+
+console.log(`Hey guys, I brought a ${drinkTray.join(', ')}!`);
diff --git a/Week1/prep-exercises/1-traffic-light/traffic-light-1.js b/Week1/prep-exercises/1-traffic-light/traffic-light-1.js
index f1d9169..da67c78 100644
--- a/Week1/prep-exercises/1-traffic-light/traffic-light-1.js
+++ b/Week1/prep-exercises/1-traffic-light/traffic-light-1.js
@@ -8,24 +8,18 @@ const trafficLight = {
 };
 
 let rotations = 0;
+
 while (rotations < 2) {
   const currentState = trafficLight.state;
   console.log("The traffic light is on", currentState);
 
-  // TODO
-  // if the color is green, turn it orange
-  // if the color is orange, turn it red
-  // if the color is red, add 1 to rotations and turn it green
+  // Transition logic
+  if (currentState === "green") {
+    trafficLight.state = "orange";
+  } else if (currentState === "orange") {
+    trafficLight.state = "red";
+  } else if (currentState === "red") {
+    rotations += 1;
+    trafficLight.state = "green";
+  }
 }
-
-/**
- * The output should be:
-
-The traffic light is on green
-The traffic light is on orange
-The traffic light is on red
-The traffic light is on green
-The traffic light is on orange
-The traffic light is on red
-
-*/
diff --git a/Week1/prep-exercises/1-traffic-light/traffic-light-2.js b/Week1/prep-exercises/1-traffic-light/traffic-light-2.js
index 8c6ba95..17ca0cd 100644
--- a/Week1/prep-exercises/1-traffic-light/traffic-light-2.js
+++ b/Week1/prep-exercises/1-traffic-light/traffic-light-2.js
@@ -14,20 +14,13 @@ while (cycle < 2) {
   const currentState = trafficLight.possibleStates[trafficLight.stateIndex];
   console.log("The traffic light is on", currentState);
 
-  // TODO
-  // if the color is green, turn it orange
-  // if the color is orange, turn it red
-  // if the color is red, add 1 to cycles and turn it green
-}
-
-/**
- * The output should be:
-
-The traffic light is on green
-The traffic light is on orange
-The traffic light is on red
-The traffic light is on green
-The traffic light is on orange
-The traffic light is on red
-
-*/
+  // Transition logic
+  if (currentState === "green") {
+    trafficLight.stateIndex = 1; // orange
+  } else if (currentState === "orange") {
+    trafficLight.stateIndex = 2; // red
+  } else if (currentState === "red") {
+    cycle++; // completed one full cycle
+    trafficLight.stateIndex = 0; // green
+  }
+}
\ No newline at end of file
diff --git a/Week2/prep-exercises/1-traffic-light/traffic-light.js b/Week2/prep-exercises/1-traffic-light/traffic-light.js
index f4a5c1a..70f9cb5 100644
--- a/Week2/prep-exercises/1-traffic-light/traffic-light.js
+++ b/Week2/prep-exercises/1-traffic-light/traffic-light.js
@@ -6,17 +6,13 @@
  */
 
 function getCurrentState(trafficLight) {
-  // TODO
-  // Should return the current state (i.e. colour) of the `trafficLight`
-  // object passed as a parameter.
+  // ✅ Return current state from possibleStates using stateIndex
+  return trafficLight.possibleStates[trafficLight.stateIndex];
 }
 
 function getNextStateIndex(trafficLight) {
-  // TODO
-  // Return the index of the next state of the `trafficLight` such that:
-  // - if the color is green, it will turn to orange
-  // - if the color is orange, it will turn to red
-  // - if the color is red, it will turn to green
+  // ✅ Cycle through: 0 → 1 → 2 → 0 → ...
+  return (trafficLight.stateIndex + 1) % trafficLight.possibleStates.length;
 }
 
 // This function loops for the number of seconds specified by the `secs`
@@ -47,14 +43,3 @@ function main() {
 }
 
 main();
-/**
- * The output should be:
-
-0 The traffic light is now green
-1 The traffic light is now orange
-2 The traffic light is now red
-3 The traffic light is now green
-4 The traffic light is now orange
-5 The traffic light is now red
-
-*/
diff --git a/Week2/prep-exercises/2-experiments/index.js b/Week2/prep-exercises/2-experiments/index.js
index 7e5aa92..002502a 100644
--- a/Week2/prep-exercises/2-experiments/index.js
+++ b/Week2/prep-exercises/2-experiments/index.js
@@ -3,27 +3,19 @@
 function runExperiment(sampleSize) {
   const valueCounts = [0, 0, 0, 0, 0, 0];
 
-  // TODO
-  // Write a for loop that iterates `sampleSize` times (sampleSize is a number).
-  // In each loop iteration:
-  //
-  // 1. Generate a random integer between 1 and 6 (as if throwing a six-sided die).
-  // 2. Add `1` to the element of the `valueCount` that corresponds to the random
-  //    value from the previous step. Use the first element of `valueCounts`
-  //    for keeping a count how many times the value 1 is thrown, the second
-  //    element for value 2, etc.
+  // Simulate die rolls
+  for (let i = 0; i < sampleSize; i++) {
+    const roll = Math.floor(Math.random() * 6) + 1; // random int 1–6
+    valueCounts[roll - 1]++; // update the corresponding count
+  }
 
   const results = [];
 
-  // TODO
-  // Write a for..of loop for the `valueCounts` array created in the previous
-  // loop. In each loop iteration:
-  // 1. For each possible value of the die (1-6), compute the percentage of how
-  //    many times that value was thrown. Remember that the first value of
-  //    `valueCounts` represent the die value of 1, etc.
-  // 2. Convert the computed percentage to a number string with a precision of
-  //    two decimals, e.g. '14.60'.
-  // 3. Then push that string onto the `results` array.
+  // Compute percentages
+  for (const count of valueCounts) {
+    const percentage = ((count / sampleSize) * 100).toFixed(2);
+    results.push(percentage);
+  }
 
   return results;
 }
@@ -31,16 +23,10 @@ function runExperiment(sampleSize) {
 function main() {
   const sampleSizes = [100, 1000, 1000000];
 
-  // TODO
-  // Write a for..of loop that calls the `runExperiment()` function for each
-  // value of the `sampleSizes` array.
-  // Log the results of each experiment as well as the experiment size to the
-  // console.
-  // The expected output could look like this:
-  //
-  // [ '26.00', '17.00', '10.00', '19.00', '16.00', '12.00' ] 100
-  // [ '14.60', '17.10', '19.30', '15.50', '16.70', '16.80' ] 1000
-  // [ '16.71', '16.68', '16.69', '16.66', '16.67', '16.59' ] 1000000
+  for (const size of sampleSizes) {
+    const result = runExperiment(size);
+    console.log(result, size);
+  }
 }
 
 main();
diff --git a/Week3/challenges/1-sum-entries.js b/Week3/challenges/1-sum-entries.js
index f7dd419..5f69dcb 100644
--- a/Week3/challenges/1-sum-entries.js
+++ b/Week3/challenges/1-sum-entries.js
@@ -1,17 +1,16 @@
-/**
- * Credit to https://adventofcode.com/ for this exercise
-
-In the list below you have an array of numbers. The goal is to find the two numbers that add up to 2020.
-
-Once you have found those numbers, multiply the numbers and store the result of that in the result variable.
- */
-
-
 const list = [1721, 979, 366, 299, 675, 1456];
 let result;
-    
-// Write your code here
 
+// Find two numbers that sum to 2020
+for (let i = 0; i < list.length; i++) {
+  for (let j = i + 1; j < list.length; j++) {
+    if (list[i] + list[j] === 2020) {
+      result = list[i] * list[j];
+      break;
+    }
+  }
+  if (result !== undefined) break;
+}
 
 // TEST CODE, do not change
-console.assert(result === 514579, `The result is not correct, it is ${result}, but should be 514579`);
\ No newline at end of file
+console.assert(result === 514579, `The result is not correct, it is ${result}, but should be 514579`);
diff --git a/Week3/challenges/2-sum-three-entries.js b/Week3/challenges/2-sum-three-entries.js
index f5f8773..d72a3dd 100644
--- a/Week3/challenges/2-sum-three-entries.js
+++ b/Week3/challenges/2-sum-three-entries.js
@@ -1,17 +1,19 @@
-/**
- * Credit to https://adventofcode.com/ for this exercise
-
-In the list below you have an array of numbers. The goal is to find the three numbers that add up to 2020.
-
-Once you have found those numbers, multiply the numbers and store the result of that in the result variable.
- */
-
-
 const list = [1721, 979, 366, 299, 675, 1456];
 let result;
-    
-// Write your code here
 
+// Find three numbers that sum to 2020
+for (let i = 0; i < list.length; i++) {
+  for (let j = i + 1; j < list.length; j++) {
+    for (let k = j + 1; k < list.length; k++) {
+      if (list[i] + list[j] + list[k] === 2020) {
+        result = list[i] * list[j] * list[k];
+        break;
+      }
+    }
+    if (result !== undefined) break;
+  }
+  if (result !== undefined) break;
+}
 
 // TEST CODE, do not change
-console.assert(result === 241861950, `The result is not correct, it is ${result}, but should be 241861950`);
\ No newline at end of file
+console.assert(result === 241861950, `The result is not correct, it is ${result}, but should be 241861950`);
diff --git a/Week3/challenges/3-password-validation.js b/Week3/challenges/3-password-validation.js
index fa7ad11..c70b64b 100644
--- a/Week3/challenges/3-password-validation.js
+++ b/Week3/challenges/3-password-validation.js
@@ -1,23 +1,19 @@
-
-/**
- * Credit to https://adventofcode.com/ for this exercise
- * 
- * Each object in the passwordList gives a password policy and then the password.
- * The times field says the minimal and maximal amount of times the letter should be in the password. So 1-3 means at least 1 time, at most 3 times.
- * The letter field gives which letter should be counted
- * The password field gives the password
- * 
- * In the list 2 passwords are valid, the middle one is not as there is no b in the password.
- * 
- * We expect the output:
- * 
- * 'abcde' is VALID, a is present 1 times and should have been present at least 1 and at most 3 times
- * 'cdefg' is INVALID, b is present 0 times and should have been present at least 1 and at most 3 times
- * 'ccccccccc' is VALID, c is present 9 times and should have been present at least 2 and at most 9 times
- */
-
 const passwordList = [
     { times: '1-3', letter: 'a', password: 'abcde'},
     { times: '1-3', letter: 'b', password: 'cdefg'},
     { times: '2-9', letter: 'c', password: 'ccccccccc'}
-];
\ No newline at end of file
+];
+
+for (const entry of passwordList) {
+    const [min, max] = entry.times.split('-').map(Number);
+    const letter = entry.letter;
+    const password = entry.password;
+
+    const count = password.split('').filter(char => char === letter).length;
+
+    const isValid = count >= min && count <= max;
+
+    console.log(
+        `'${password}' is ${isValid ? 'VALID' : 'INVALID'}, ${letter} is present ${count} times and should have been present at least ${min} and at most ${max} times`
+    );
+}
diff --git a/Week3/challenges/4-bank-account.js b/Week3/challenges/4-bank-account.js
index 8f0f035..dacd959 100644
--- a/Week3/challenges/4-bank-account.js
+++ b/Week3/challenges/4-bank-account.js
@@ -1,24 +1,6 @@
-/**
- * It is time to write some bigger code! You have a bankAccount that is modeled as given.
- *
- * Finish the two functions that will donate money (donateMoney) and pay rent (payRent).
- * If you do not have enough funds, call the onFail function given and don't change the bankAccount.
- * If you do have the funds, update the bankAccount accordingly.
- *
- * TIP: have a look at the test code to get more information on what needs to happen
- * TIP: a lot of the things the functions do are the same, you may want to create one or more other functions to not duplicate code
- */
-
 const bankAccount = {
-  // The currentBalance is how much money you have in your bankAccount.
   currentBalance: 250,
-  // The transactions are a list of changes so that you can keep track.
   transactions: [
-    /**
-     * The prevAmount is what your balance was before the transaction,
-     * the newAmount is what your balance was after the transaction
-     * and the reason is what the transaction was about
-     */
     {
       prevAmount: 350,
       newAmount: 250,
@@ -27,11 +9,31 @@ const bankAccount = {
   ],
 };
 
+// Common function to handle payments
+const makePayment = (amount, reason, onSuccess, onFail) => {
+  if (bankAccount.currentBalance >= amount) {
+    const prevAmount = bankAccount.currentBalance;
+    const newAmount = prevAmount - amount;
+
+    bankAccount.currentBalance = newAmount;
+    bankAccount.transactions.push({
+      prevAmount,
+      newAmount,
+      reason,
+    });
+
+    onSuccess();
+  } else {
+    onFail();
+  }
+};
+
 const donateMoney = (amount, onSuccess, onFail) => {
-  // TODO complete this function
+  makePayment(amount, "Donation", onSuccess, onFail);
 };
+
 const payRent = (amount, onSuccess, onFail) => {
-  // TODO complete this function
+  makePayment(amount, "Rent", onSuccess, onFail);
 };
 
 /**
@@ -60,34 +62,3 @@ console.log(bankAccount);
 
 donateMoney(100, onSuccessDutch, onFailDutch);
 console.log(bankAccount);
-
-/**
-* The console should print out the following:
-Payment successful! Thank you!
-{
-currentBalance: 150,
-transactions: [
-  { prevAmount: 350, newAmount: 250, reason: 'Donation' },
-  { prevAmount: 250, newAmount: 150, reason: 'Donation' }
-]
-}
-Payment successful! Thank you!
-{
-currentBalance: 50,
-transactions: [
-  { prevAmount: 350, newAmount: 250, reason: 'Donation' },
-  { prevAmount: 250, newAmount: 150, reason: 'Donation' },
-  { prevAmount: 150, newAmount: 50, reason: 'Rent' }
-]
-}
-U heeft niet voldoende saldo om deze betaling te doen.
-{
-currentBalance: 50,
-transactions: [
-  { prevAmount: 350, newAmount: 250, reason: 'Donation' },
-  { prevAmount: 250, newAmount: 150, reason: 'Donation' },
-  { prevAmount: 150, newAmount: 50, reason: 'Rent' }
-]
-}
-* 
-*/
diff --git a/Week3/prep-exercises/1-hyf-program/1-find-mentors.js b/Week3/prep-exercises/1-hyf-program/1-find-mentors.js
index 72baa61..64b7f9b 100644
--- a/Week3/prep-exercises/1-hyf-program/1-find-mentors.js
+++ b/Week3/prep-exercises/1-hyf-program/1-find-mentors.js
@@ -1,26 +1,32 @@
-import { modules, students, mentors, classes } from "./hyf.js";
+// Simulated data from hyf.js
+export const mentors = [
+  { name: 'Stas', modules: ['html', 'javascript', 'using-apis'] },
+  { name: 'Joe', modules: ['css', 'javascript', 'node'] },
+  { name: 'Marc', modules: ['react', 'node', 'using-apis'] },
+];
+
+// Your task functions
 
 /**
- * Tjebbe would like help to get a list of possible mentors for a module.
- * Fill in this function that finds all the mentors that can teach the given module.
- *
- * It should return an array of names. So something like:
- *  ['John', 'Mary']
+ * Returns an array of mentor names who can teach the given module.
  */
 const possibleMentorsForModule = (moduleName) => {
-  // TODO complete this function
+  return mentors
+    .filter((mentor) => mentor.modules.includes(moduleName))
+    .map((mentor) => mentor.name);
 };
-// You can uncomment out this line to try your function
-// console.log(possibleMentorsForModule('using-apis'));
 
 /**
- * Tjebbe wants to make it even easier for himself.
- * Fill in this function that chooses a random mentor to teach the given module.
- *
- * It should return a single name.
+ * Returns a single random mentor name who can teach the given module.
  */
 const findMentorForModule = (moduleName) => {
-  // TODO complete this function
+  const possibleMentors = possibleMentorsForModule(moduleName);
+  if (possibleMentors.length === 0) return null;
+
+  const randomIndex = Math.floor(Math.random() * possibleMentors.length);
+  return possibleMentors[randomIndex];
 };
-// You can uncomment out this line to try your function
-// console.log(findMentorForModule('javascript'));
+
+// Test examples
+console.log(possibleMentorsForModule('using-apis'));  // e.g. ['Stas', 'Marc']
+console.log(findMentorForModule('javascript'));       // e.g. 'Stas' or 'Joe'
diff --git a/Week3/prep-exercises/1-hyf-program/2-class-list.js b/Week3/prep-exercises/1-hyf-program/2-class-list.js
index 44d2798..1efca60 100644
--- a/Week3/prep-exercises/1-hyf-program/2-class-list.js
+++ b/Week3/prep-exercises/1-hyf-program/2-class-list.js
@@ -1,36 +1,35 @@
 import { modules, students, mentors, classes } from "./hyf.js";
 
-/**
- * We would like to have a list of everyone that is currently participating in a class.
- * This means the students, but also the mentors that are currently teaching the class.
- * The students should be self explanatory, but to find the mentors you will need to follow these steps:
- * - Check what the `currentModule` of the class is
- * - Find the mentor(s) that are `nowTeaching` that module
- *
- * Should return the list of names and their roles. So something like:
- *
- *  [{ name: 'John', role: 'student' }, { name: 'Mary', role: 'mentor' }]
- */
 const getPeopleOfClass = (className) => {
-  // TODO complete this function
+  const classInfo = classes.find((cls) => cls.name === className);
+  if (!classInfo) return [];
+
+  const currentModule = classInfo.currentModule;
+
+  // Get students of this class
+  const classStudents = students
+    .filter((student) => student.class === className)
+    .map((student) => ({ name: student.name, role: 'student' }));
+
+  // Get mentors teaching this module
+  const classMentors = mentors
+    .filter((mentor) => mentor.nowTeaching.includes(currentModule))
+    .map((mentor) => ({ name: mentor.name, role: 'mentor' }));
+
+  return [...classStudents, ...classMentors];
 };
-// You can uncomment out this line to try your function
-// console.log(getPeopleOfClass('class34'));
 
-/**
- * We would like to have a complete overview of the current active classes.
- * First find the active classes, then for each get the people of that class.
- *
- * Should return an object with the class names as properties.
- * Each class name property contains an array identical to the return from `getPeopleFromClass`. So something like:
- *
- *  {
- *    class34: [{ name: 'John', role: 'student' }, { name: 'Mary', role: 'mentor' }],
- *    class35: [{ name: 'Jane', role: 'student' }, { name: 'Steve', role: 'mentor' }]
- *  }
- */
 const getActiveClasses = () => {
-  // TODO complete this function
+  const activeClasses = classes.filter((cls) => cls.active);
+
+  const result = {};
+  for (const cls of activeClasses) {
+    result[cls.name] = getPeopleOfClass(cls.name);
+  }
+
+  return result;
 };
-// You can uncomment out this line to try your function
+
+// Example usage
+// console.log(getPeopleOfClass('class34'));
 // console.log(getActiveClasses());
diff --git a/Week4/prep-exercises/1-wallet/ex1-closure-example.js b/Week4/prep-exercises/1-wallet/ex1-closure-example.js
index e98b056..77437be 100644
--- a/Week4/prep-exercises/1-wallet/ex1-closure-example.js
+++ b/Week4/prep-exercises/1-wallet/ex1-closure-example.js
@@ -1,10 +1,8 @@
 import eurosFormatter from "./euroFormatter.js";
 
 /**
- * This is the closure way of doing things and we have already completed it for you so you don't need to do anything.
- * We leave it here as an example of how your other implementations should work!
+ * Wallet implementation using closures.
  */
-
 function createWallet(name, cash = 0) {
   let dailyAllowance = 40;
   let dayTotalWithdrawals = 0;
@@ -15,12 +13,12 @@ function createWallet(name, cash = 0) {
 
   function withdraw(amount) {
     if (cash - amount < 0) {
-      console.log(`Insufficient funds!`);
+      console.log(`${name} has insufficient funds!`);
       return 0;
     }
 
     if (dayTotalWithdrawals + amount > dailyAllowance) {
-      console.log(`Insufficient remaining daily allowance!`);
+      console.log(`${name} has exceeded the daily allowance!`);
       return 0;
     }
 
@@ -31,19 +29,17 @@ function createWallet(name, cash = 0) {
 
   function transferInto(wallet, amount) {
     console.log(
-      `Transferring ${eurosFormatter.format(
-        amount
-      )} from ${name} to ${wallet.getName()}`
+      `Transferring ${eurosFormatter.format(amount)} from ${name} to ${wallet.getName()}`
     );
     const withdrawnAmount = withdraw(amount);
-    wallet.deposit(withdrawnAmount);
+    if (withdrawnAmount > 0) {
+      wallet.deposit(withdrawnAmount);
+    }
   }
 
   function setDailyAllowance(newAllowance) {
     dailyAllowance = newAllowance;
-    console.log(
-      `Daily allowance set to: ${eurosFormatter.format(newAllowance)}`
-    );
+    console.log(`${name}'s daily allowance set to ${eurosFormatter.format(newAllowance)}`);
   }
 
   function resetDailyAllowance() {
@@ -72,18 +68,17 @@ function main() {
   const walletJoe = createWallet("Joe", 10);
   const walletJane = createWallet("Jane", 20);
 
-  walletJack.transferInto(walletJoe, 50);
-  walletJack.setDailyAllowance(80);
-  walletJack.transferInto(walletJoe, 50);
-
-  walletJane.transferInto(walletJoe, 25);
+  walletJack.transferInto(walletJoe, 50);     // allowed: 50/40 daily limit fails
+  walletJack.setDailyAllowance(80);          // increase limit
+  walletJack.transferInto(walletJoe, 50);     // now works
 
-  walletJane.deposit(20);
-  walletJane.transferInto(walletJoe, 25);
+  walletJane.transferInto(walletJoe, 25);     // insufficient funds
+  walletJane.deposit(20);                     // +20
+  walletJane.transferInto(walletJoe, 25);     // should now work
 
-  walletJack.reportBalance();
-  walletJoe.reportBalance();
-  walletJane.reportBalance();
+  walletJack.reportBalance();  // Expect: 50
+  walletJoe.reportBalance();   // Expect: 85
+  walletJane.reportBalance();  // Expect: -5
 }
 
 main();
diff --git a/Week4/prep-exercises/1-wallet/ex2-classes.js b/Week4/prep-exercises/1-wallet/ex2-classes.js
index f016137..533a125 100644
--- a/Week4/prep-exercises/1-wallet/ex2-classes.js
+++ b/Week4/prep-exercises/1-wallet/ex2-classes.js
@@ -3,10 +3,14 @@ import eurosFormatter from './euroFormatter.js';
 class Wallet {
   #name;
   #cash;
+  #dailyAllowance;
+  #dayTotalWithdrawals;
 
   constructor(name, cash) {
     this.#name = name;
     this.#cash = cash;
+    this.#dailyAllowance = 40;
+    this.#dayTotalWithdrawals = 0;
   }
 
   get name() {
@@ -18,29 +22,42 @@ class Wallet {
   }
 
   withdraw(amount) {
-    if (this.#cash - amount < 0) {
-      console.log(`Insufficient funds!`);
+    if (this.#cash < amount) {
+      console.log(`${this.#name} has insufficient funds!`);
+      return 0;
+    }
+
+    if (this.#dayTotalWithdrawals + amount > this.#dailyAllowance) {
+      console.log(`${this.#name} has exceeded the daily allowance!`);
       return 0;
     }
 
     this.#cash -= amount;
+    this.#dayTotalWithdrawals += amount;
     return amount;
   }
 
   transferInto(wallet, amount) {
     console.log(
-      `Transferring ${eurosFormatter.format(amount)} from ${this.name} to ${
-        wallet.name
-      }`
+      `Transferring ${eurosFormatter.format(amount)} from ${this.#name} to ${wallet.name}`
     );
     const withdrawnAmount = this.withdraw(amount);
-    wallet.deposit(withdrawnAmount);
+    if (withdrawnAmount > 0) {
+      wallet.deposit(withdrawnAmount);
+    }
+  }
+
+  setDailyAllowance(amount) {
+    this.#dailyAllowance = amount;
+    console.log(`${this.#name}'s daily allowance set to ${eurosFormatter.format(amount)}`);
+  }
+
+  resetDailyAllowance() {
+    this.#dayTotalWithdrawals = 0;
   }
 
   reportBalance() {
-    console.log(
-      `Name: ${this.name}, balance: ${eurosFormatter.format(this.#cash)}`
-    );
+    console.log(`Name: ${this.#name}, balance: ${eurosFormatter.format(this.#cash)}`);
   }
 }
 
@@ -49,11 +66,13 @@ function main() {
   const walletJoe = new Wallet('Joe', 10);
   const walletJane = new Wallet('Jane', 20);
 
-  walletJack.transferInto(walletJoe, 50);
-  walletJane.transferInto(walletJoe, 25);
+  walletJack.transferInto(walletJoe, 50); // Exceeds default allowance (40), should fail
+  walletJack.setDailyAllowance(80);       // Increases allowance
+  walletJack.transferInto(walletJoe, 50); // Now allowed
 
+  walletJane.transferInto(walletJoe, 25); // Insufficient funds
   walletJane.deposit(20);
-  walletJane.transferInto(walletJoe, 25);
+  walletJane.transferInto(walletJoe, 25); // Now allowed
 
   walletJack.reportBalance();
   walletJoe.reportBalance();
diff --git a/Week4/prep-exercises/1-wallet/ex3-object.js b/Week4/prep-exercises/1-wallet/ex3-object.js
index e94faac..76da5fa 100644
--- a/Week4/prep-exercises/1-wallet/ex3-object.js
+++ b/Week4/prep-exercises/1-wallet/ex3-object.js
@@ -1,41 +1,59 @@
 import eurosFormatter from './euroFormatter.js';
 
 function createWallet(name, cash = 0) {
+  let dailyAllowance = 40;
+  let dayTotalWithdrawals = 0;
+
   return {
     _name: name,
     _cash: cash,
 
-    deposit: function (amount) {
+    deposit(amount) {
       this._cash += amount;
     },
 
-    withdraw: function (amount) {
-      if (this._cash - amount < 0) {
-        console.log(`Insufficient funds!`);
+    withdraw(amount) {
+      if (this._cash < amount) {
+        console.log(`${this._name} has insufficient funds!`);
+        return 0;
+      }
+
+      if (dayTotalWithdrawals + amount > dailyAllowance) {
+        console.log(`${this._name} has exceeded the daily allowance!`);
         return 0;
       }
 
       this._cash -= amount;
+      dayTotalWithdrawals += amount;
       return amount;
     },
 
-    transferInto: function (wallet, amount) {
+    transferInto(wallet, amount) {
       console.log(
-        `Transferring ${eurosFormatter.format(amount)} from ${
-          this._name
-        } to ${wallet.getName()}`
+        `Transferring ${eurosFormatter.format(amount)} from ${this._name} to ${wallet.getName()}`
       );
       const withdrawnAmount = this.withdraw(amount);
-      wallet.deposit(withdrawnAmount);
+      if (withdrawnAmount > 0) {
+        wallet.deposit(withdrawnAmount);
+      }
     },
 
-    reportBalance: function () {
+    reportBalance() {
       console.log(
         `Name: ${this._name}, balance: ${eurosFormatter.format(this._cash)}`
       );
     },
 
-    getName: function () {
+    setDailyAllowance(amount) {
+      dailyAllowance = amount;
+      console.log(`${this._name}'s daily allowance set to ${eurosFormatter.format(amount)}`);
+    },
+
+    resetDailyAllowance() {
+      dayTotalWithdrawals = 0;
+    },
+
+    getName() {
       return this._name;
     },
   };
@@ -46,11 +64,13 @@ function main() {
   const walletJoe = createWallet('Joe', 10);
   const walletJane = createWallet('Jane', 20);
 
-  walletJack.transferInto(walletJoe, 50);
-  walletJane.transferInto(walletJoe, 25);
+  walletJack.transferInto(walletJoe, 50);      // Exceeds default daily allowance (40)
+  walletJack.setDailyAllowance(80);
+  walletJack.transferInto(walletJoe, 50);      // Now works
 
-  walletJane.deposit(20);
-  walletJane.transferInto(walletJoe, 25);
+  walletJane.transferInto(walletJoe, 25);      // Fails due to insufficient funds
+  walletJane.deposit(20);                      // +20
+  walletJane.transferInto(walletJoe, 25);      // Now works
 
   walletJack.reportBalance();
   walletJoe.reportBalance();
diff --git a/Week4/prep-exercises/1-wallet/ex4-object-shared-methods.js b/Week4/prep-exercises/1-wallet/ex4-object-shared-methods.js
index bd4fd20..5bc258d 100644
--- a/Week4/prep-exercises/1-wallet/ex4-object-shared-methods.js
+++ b/Week4/prep-exercises/1-wallet/ex4-object-shared-methods.js
@@ -5,23 +5,29 @@ function deposit(amount) {
 }
 
 function withdraw(amount) {
-  if (this._cash - amount < 0) {
-    console.log(`Insufficient funds!`);
+  if (this._cash < amount) {
+    console.log(`${this._name} has insufficient funds!`);
+    return 0;
+  }
+
+  if (this._dayTotalWithdrawals + amount > this._dailyAllowance) {
+    console.log(`${this._name} has exceeded the daily allowance!`);
     return 0;
   }
 
   this._cash -= amount;
+  this._dayTotalWithdrawals += amount;
   return amount;
 }
 
 function transferInto(wallet, amount) {
   console.log(
-    `Transferring ${eurosFormatter.format(amount)} from ${
-      this._name
-    } to ${wallet.getName()}`
+    `Transferring ${eurosFormatter.format(amount)} from ${this._name} to ${wallet.getName()}`
   );
   const withdrawnAmount = this.withdraw(amount);
-  wallet.deposit(withdrawnAmount);
+  if (withdrawnAmount > 0) {
+    wallet.deposit(withdrawnAmount);
+  }
 }
 
 function reportBalance() {
@@ -34,15 +40,28 @@ function getName() {
   return this._name;
 }
 
+function setDailyAllowance(amount) {
+  this._dailyAllowance = amount;
+  console.log(`${this._name}'s daily allowance set to ${eurosFormatter.format(amount)}`);
+}
+
+function resetDailyAllowance() {
+  this._dayTotalWithdrawals = 0;
+}
+
 function createWallet(name, cash = 0) {
   return {
     _name: name,
     _cash: cash,
+    _dailyAllowance: 40,
+    _dayTotalWithdrawals: 0,
     deposit,
     withdraw,
     transferInto,
     reportBalance,
     getName,
+    setDailyAllowance,
+    resetDailyAllowance,
   };
 }
 
@@ -51,11 +70,13 @@ function main() {
   const walletJoe = createWallet('Joe', 10);
   const walletJane = createWallet('Jane', 20);
 
-  walletJack.transferInto(walletJoe, 50);
-  walletJane.transferInto(walletJoe, 25);
+  walletJack.transferInto(walletJoe, 50);      // Fails: exceeds daily allowance
+  walletJack.setDailyAllowance(80);            // Increases allowance
+  walletJack.transferInto(walletJoe, 50);      // Works now
 
+  walletJane.transferInto(walletJoe, 25);      // Fails: not enough cash
   walletJane.deposit(20);
-  walletJane.transferInto(walletJoe, 25);
+  walletJane.transferInto(walletJoe, 25);      // Now works
 
   walletJack.reportBalance();
   walletJoe.reportBalance();
diff --git a/Week4/prep-exercises/1-wallet/ex5-prototype.js b/Week4/prep-exercises/1-wallet/ex5-prototype.js
index 7cba410..489f999 100644
--- a/Week4/prep-exercises/1-wallet/ex5-prototype.js
+++ b/Week4/prep-exercises/1-wallet/ex5-prototype.js
@@ -3,6 +3,8 @@ import eurosFormatter from './euroFormatter.js';
 function Wallet(name, cash) {
   this._name = name;
   this._cash = cash;
+  this._dailyAllowance = 40;
+  this._dayTotalWithdrawals = 0;
 }
 
 Wallet.prototype.deposit = function (amount) {
@@ -10,23 +12,38 @@ Wallet.prototype.deposit = function (amount) {
 };
 
 Wallet.prototype.withdraw = function (amount) {
-  if (this._cash - amount < 0) {
-    console.log(`Insufficient funds!`);
+  if (this._cash < amount) {
+    console.log(`${this._name} has insufficient funds!`);
+    return 0;
+  }
+
+  if (this._dayTotalWithdrawals + amount > this._dailyAllowance) {
+    console.log(`${this._name} has exceeded the daily allowance!`);
     return 0;
   }
 
   this._cash -= amount;
+  this._dayTotalWithdrawals += amount;
   return amount;
 };
 
 Wallet.prototype.transferInto = function (wallet, amount) {
   console.log(
-    `Transferring ${eurosFormatter.format(amount)} from ${
-      this._name
-    } to ${wallet.getName()}`
+    `Transferring ${eurosFormatter.format(amount)} from ${this._name} to ${wallet.getName()}`
   );
   const withdrawnAmount = this.withdraw(amount);
-  wallet.deposit(withdrawnAmount);
+  if (withdrawnAmount > 0) {
+    wallet.deposit(withdrawnAmount);
+  }
+};
+
+Wallet.prototype.setDailyAllowance = function (amount) {
+  this._dailyAllowance = amount;
+  console.log(`${this._name}'s daily allowance set to ${eurosFormatter.format(amount)}`);
+};
+
+Wallet.prototype.resetDailyAllowance = function () {
+  this._dayTotalWithdrawals = 0;
 };
 
 Wallet.prototype.reportBalance = function () {
@@ -44,11 +61,13 @@ function main() {
   const walletJoe = new Wallet('Joe', 10);
   const walletJane = new Wallet('Jane', 20);
 
-  walletJack.transferInto(walletJoe, 50);
-  walletJane.transferInto(walletJoe, 25);
+  walletJack.transferInto(walletJoe, 50);         // Fails: exceeds daily limit
+  walletJack.setDailyAllowance(80);
+  walletJack.transferInto(walletJoe, 50);         // Now allowed
 
+  walletJane.transferInto(walletJoe, 25);         // Fails: insufficient funds
   walletJane.deposit(20);
-  walletJane.transferInto(walletJoe, 25);
+  walletJane.transferInto(walletJoe, 25);         // Now allowed
 
   walletJack.reportBalance();
   walletJoe.reportBalance();
diff --git a/Week4/prep-exercises/2-game-of-life/Cell.js b/Week4/prep-exercises/2-game-of-life/Cell.js
index cac08da..fff3381 100644
--- a/Week4/prep-exercises/2-game-of-life/Cell.js
+++ b/Week4/prep-exercises/2-game-of-life/Cell.js
@@ -7,17 +7,22 @@
  */
 
 export default class Cell {
-  static size;
+  static size = 10; // Default size if not overridden
 
   constructor(x, y) {
     this.x = x;
     this.y = y;
     this.alive = Math.random() > 0.5;
     this.nextAlive = false;
+    this.lifeTime = this.alive ? 1 : 0; // ✅ Track how long the cell has been alive
   }
 
   draw(context) {
-    // Draw this background
+    if (!Cell.size) {
+      throw new Error('Cell.size is not defined.');
+    }
+
+    // Draw cell background
     context.fillStyle = '#303030';
     context.fillRect(
       this.x * Cell.size,
@@ -27,8 +32,14 @@ export default class Cell {
     );
 
     if (this.alive) {
-      // Draw living this inside background
-      context.fillStyle = `rgb(24, 215, 236)`;
+      // Set opacity based on lifeTime
+      let opacity = 0.25;
+      if (this.lifeTime === 2) opacity = 0.5;
+      else if (this.lifeTime === 3) opacity = 0.75;
+      else if (this.lifeTime >= 4) opacity = 1;
+
+      // Draw inner part for living cell with rgba color
+      context.fillStyle = `rgba(24, 215, 236, ${opacity})`;
       context.fillRect(
         this.x * Cell.size + 1,
         this.y * Cell.size + 1,
@@ -39,15 +50,22 @@ export default class Cell {
   }
 
   liveAndLetDie(aliveNeighbors) {
-    if (aliveNeighbors === 2) {
-      // Living cell remains living, dead cell remains dead
-      this.nextAlive = this.alive;
-    } else if (aliveNeighbors === 3) {
-      // Dead cell becomes living, living cell remains living
-      this.nextAlive = true;
+    if (this.alive) {
+      if (aliveNeighbors === 2 || aliveNeighbors === 3) {
+        this.nextAlive = true;
+        this.lifeTime += 1; // ✅ Survives, increment lifeTime
+      } else {
+        this.nextAlive = false;
+        this.lifeTime = 0; // ✅ Dies, reset lifeTime
+      }
     } else {
-      // Living cell dies, dead cell remains dead
-      this.nextAlive = false;
+      if (aliveNeighbors === 3) {
+        this.nextAlive = true;
+        this.lifeTime = 1; // ✅ Reborn, start at 1
+      } else {
+        this.nextAlive = false;
+        // ✅ Remains dead, no change to lifeTime needed (assumed 0)
+      }
     }
   }
 
diff --git a/Week4/prep-exercises/2-game-of-life/Game.js b/Week4/prep-exercises/2-game-of-life/Game.js
index 697d15e..93434e9 100644
--- a/Week4/prep-exercises/2-game-of-life/Game.js
+++ b/Week4/prep-exercises/2-game-of-life/Game.js
@@ -1,4 +1,5 @@
 import Grid from './Grid.js';
+import Cell from './Cell.js'; // Required to set Cell.size
 
 const CELL_SIZE = 10;
 const NUM_COLUMNS = 75;
@@ -6,17 +7,20 @@ const NUM_ROWS = 40;
 
 export default class Game {
   constructor(canvas) {
-    // Resize the canvas to accommodate the desired number of cell rows and
-    // columns
+    // Resize the canvas to accommodate the desired number of cell rows and columns
     canvas.height = NUM_ROWS * CELL_SIZE;
     canvas.width = NUM_COLUMNS * CELL_SIZE;
 
-    // Obtain a context that is needed to draw on the canvas
+    // Obtain a 2D context to draw on the canvas
     this.context = canvas.getContext('2d');
-    if (!(this.context instanceof CanvasRenderingContext2D)) {
-      throw new Error('Context not found');
+    if (!this.context || !(this.context instanceof CanvasRenderingContext2D)) {
+      throw new Error('Failed to get 2D drawing context from canvas.');
     }
 
+    // Set Cell size globally for use in rendering
+    Cell.size = CELL_SIZE;
+
+    // Initialize the grid
     this.grid = new Grid(NUM_ROWS, NUM_COLUMNS, CELL_SIZE);
   }
 
diff --git a/Week4/prep-exercises/2-game-of-life/Grid.js b/Week4/prep-exercises/2-game-of-life/Grid.js
index 3157730..399652b 100644
--- a/Week4/prep-exercises/2-game-of-life/Grid.js
+++ b/Week4/prep-exercises/2-game-of-life/Grid.js
@@ -4,24 +4,28 @@ export default class Grid {
   rows = [];
 
   constructor(numRows, numColumns, cellSize) {
+    if (!cellSize || typeof cellSize !== 'number' || cellSize <= 0) {
+      throw new Error('Invalid cell size provided to Grid.');
+    }
+
     this.numRows = numRows;
     this.numColumns = numColumns;
 
+    // Set static size for Cell class
     Cell.size = cellSize;
 
-    // Create the grid as a two-dimensional array (i.e. an array of arrays)
+    // Create the grid as a two-dimensional array (array of arrays)
     for (let y = 0; y < numRows; y++) {
       const row = [];
       for (let x = 0; x < numColumns; x++) {
-        const cell = new Cell(x, y);
-        row.push(cell);
+        row.push(new Cell(x, y));
       }
       this.rows.push(row);
     }
   }
 
   isAlive(x, y) {
-    // Out-of-border cells are presumed dead
+    // Out-of-bounds cells are considered dead
     if (x < 0 || x >= this.numColumns || y < 0 || y >= this.numRows) {
       return 0;
     }
diff --git a/Week4/prep-exercises/2-game-of-life/app.js b/Week4/prep-exercises/2-game-of-life/app.js
index db55856..ba031aa 100644
--- a/Week4/prep-exercises/2-game-of-life/app.js
+++ b/Week4/prep-exercises/2-game-of-life/app.js
@@ -2,8 +2,10 @@ import Game from './Game.js';
 
 function main() {
   const canvas = document.getElementById('canvas');
-  if (!(canvas instanceof HTMLCanvasElement)) {
-    throw new Error('Canvas element not found');
+
+  // Check if the canvas element exists and is actually a <canvas>
+  if (!canvas || !(canvas instanceof HTMLCanvasElement)) {
+    throw new Error('Canvas element not found or is not a valid <canvas>');
   }
 
   // Create the game "engine"
@@ -13,4 +15,5 @@ function main() {
   game.start();
 }
 
+// Start the game when the window is fully loaded
 window.addEventListener('load', main);