diff --git a/.vscode/extensions.json b/.vscode/extensions.json
deleted file mode 100644
index 255490743..000000000
--- a/.vscode/extensions.json
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-  "recommendations": [
-    "esbenp.prettier-vscode",
-    "dbaeumer.vscode-eslint",
-    "streetsidesoftware.code-spell-checker",
-    "eamodio.gitlens",
-    "ritwickdey.LiveServer",
-    "vsliveshare.vsliveshare"
-  ]
-}
diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..a8e3fd8a5 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,4 +1,10 @@
 // Predict and explain first...
+// This code is intended to log the house number from an address object.
+// However, it seems that the console log is not functioning as expected and the result is undefined.
+// The issue lies in the way the property is being accessed from the address object.
+// to fix this, we need to access the property using the correct key.
+
+
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +18,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address.houseNumber}`);
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..c4a8c06b0 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,4 +1,9 @@
 // Predict and explain first...
+// This code is intended to log out all the property values in the `author` object.
+// However, it is not working because the `for...of` loop is designed to iterate
+// over iterable objects like arrays or strings, but the `author` object is a plain object
+// which is not iterable. To fix this, we can use `Object.values()` to get
+// an array of the object's values, which can then be iterated over with a `for...of` loop.
 
 // This program attempts to log out all the property values in the object.
 // But it isn't working. Explain why first and then fix the problem
@@ -11,6 +16,7 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const key in author) {
+  const value = author[key];
   console.log(value);
 }
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..a7a8811cc 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,4 +1,9 @@
 // Predict and explain first...
+// This code is intended to log out the title, how many it serves, and the ingredients of a recipe.
+// However, it is not working correctly because the `console.log` statement is trying to log
+// the entire `recipe` object directly, which will not format the ingredients as expected.
+// Instead, we need to iterate over the `ingredients` array and log each ingredient on a new line.
+// To fix this, we can use a template literal to format the output and use `join` to create a string of ingredients separated by new lines.
 
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
@@ -10,6 +15,6 @@ const recipe = {
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+console.log(`${recipe.title} serves ${recipe.serves} 
+ingredients: 
+${recipe.ingredients.join('\n')}`);
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..29d4115f6 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,13 @@
-function contains() {}
+function contains(object, property) {
+    const keysArray = Object.keys(object); // Converts object keys to an array
+  
+    for (let i = 0; i < keysArray.length; i++) {
+      if (keysArray[i] === property) {
+        return true;
+      }
+    }
+  
+    return false; // Property wasn't found
+  }
 
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..90ec56fe2 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -16,20 +16,41 @@ as the object doesn't contains a key of 'c'
 // Given a contains function
 // When passed an object and a property name
 // Then it should return true if the object contains the property, false otherwise
+test("contains returns true for existing property", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, 'a')).toBe(true);
+});
 
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
-
+test("contains returns false for empty object", () => {
+  const obj = {};
+  expect(contains(obj, 'a')).toBe(false);
+});
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
 
+test("contains returns true for existing property in object", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, 'b')).toBe(true);
+});
+
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
 
+test("contains returns false for non-existent property in object", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, 'c')).toBe(false);
+});
+
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("contains returns false for invalid parameters", () => {
+  const arr = [1, 2, 3];
+  expect(contains(arr, 'length')).toBe(false);
+});
+
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..3a73d7d93 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,15 @@
-function createLookup() {
-  // implementation here
+function createLookup(pairs) {
+  const result = {};
+  for (const [country, currency] of pairs) {
+    result[country] = currency;
+  }
+  return result;
 }
 
-module.exports = createLookup;
+
+// Example usage:
+ //const countryCurrencyPairs = [['US', 'USD'], ['CA', 'CAD']];
+ //const lookup = createLookup([['US', 'USD'],['CA', 'CAD']]);
+ //console.log(lookup); // { US: 'USD', CA: 'CAD' }
+
+ module.exports = createLookup;
\ No newline at end of file
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..9145761fd 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,7 +1,13 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
+test("createLookup returns an object with country codes as keys and currency codes as values", () => {
+  const countryCurrencyPairs = [['US', 'USD'], ['CA', 'CAD']];
+  const expectedLookup = {
+    'US': 'USD',
+    'CA': 'CAD'
+  };
+  expect(createLookup(countryCurrencyPairs)).toEqual(expectedLookup);
+});
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..5e00686cc 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -1,16 +1,26 @@
 function parseQueryString(queryString) {
-  const queryParams = {};
-  if (queryString.length === 0) {
-    return queryParams;
-  }
-  const keyValuePairs = queryString.split("&");
+  if (!queryString) return {};
+
+  const result = {};
+  const pairs = queryString.split("&");
+
+  for (const pair of pairs) {
+    const index = pair.indexOf("=");
+    let key, value;
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    if (index === -1) {
+      key = decodeURIComponent(pair);
+      value = "";
+    } else {
+      key = decodeURIComponent(pair.slice(0, index));
+      value = decodeURIComponent(pair.slice(index + 1));
+    }
+
+    result[key] = value;
   }
 
-  return queryParams;
+  return result;
 }
 
+
 module.exports = parseQueryString;
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..1985bd139 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -10,3 +10,25 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+test("parses querystring with multiple values for the same key", () => {
+  expect(parseQueryString("name=John&name=Jane")).toEqual({
+    "name": "Jane",
+  });
+});
+
+test("parses querystring with empty values", () => {
+  expect(parseQueryString("name=&age=&city=")).toEqual({
+    "name": "",
+    "age": "",
+    "city": "",
+  });
+});
+
+test("parses querystring with only keys", () => {
+  expect(parseQueryString("name=&age&city")).toEqual({
+    "name": "",
+    "age": "",
+    "city": "",
+  });
+});
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..eb947dfe0 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,14 @@
-function tally() {}
+function tally(items) {
+    if (!Array.isArray(items)) {
+      throw new Error("Input must be an array");
+    }
+  
+    const counts = {};
+    for (const item of items) {
+      counts[item] = (counts[item] || 0) + 1;
+    }
+  
+    return counts;
+  }
 
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..999389d43 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -20,15 +20,42 @@ const tally = require("./tally.js");
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
 
+test("tally returns counts for each unique item", () => {
+  const items = ['a', 'b', 'a', 'c', 'b', 'a'];
+  const expectedOutput = { a: 3, b: 2, c: 1 };
+  expect(tally(items)).toEqual(expectedOutput);
+});
 // Given an empty array
 // When passed to tally
 // Then it should return an empty object
-test.todo("tally on an empty array returns an empty object");
-
+test("tally returns empty object for empty array", () => {
+  const items = [];
+  expect(tally(items)).toEqual({});
+});
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("tally returns counts for duplicate items", () => {
+  const items = ['x', 'y', 'x', 'z', 'y', 'x'];
+  const expectedOutput = { x: 3, y: 2, z: 1 };
+  expect(tally(items)).toEqual(expectedOutput);
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("tally throws error for invalid input", () => {
+  expect(() => tally("invalid")).toThrow("Input must be an array");
+});
+
+test("tally throws for number input", () => {
+    expect(() => tally(123)).toThrow("Input must be an array");
+  });
+  
+  test("tally throws for object input", () => {
+    expect(() => tally({ a: 1 })).toThrow("Input must be an array");
+  });
+  
+  test("tally throws for null input", () => {
+    expect(() => tally(null)).toThrow("Input must be an array");
+  });
\ No newline at end of file
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..1d40ca689 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -16,14 +16,30 @@ function invert(obj) {
   return invertedObj;
 }
 
+
 // a) What is the current return value when invert is called with { a : 1 }
+// The current return value when invert is called with { a: 1 } is { key: 1 }.
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// The current return value when invert is called with { a: 1, b: 2 } is { key: 2 }.
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// The target return value when invert is called with { a: 1, b: 2 } should be { "1": "a", "2": "b" }.
 
 // c) What does Object.entries return? Why is it needed in this program?
+// Object.entries returns an array of key-value pairs from the object.
+// It is needed in this program to iterate over the object's properties and their corresponding values.
 
 // d) Explain why the current return value is different from the target output
+// The current return value is different from the target output because the code incorrectly assigns the value to the key in the inverted object.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+function invert(obj) {
+  const invertedObj = {};
+
+  for (const [key, value] of Object.entries(obj)) {
+    invertedObj[value] = key;
+  }
+
+  return invertedObj;
+}
diff --git a/Sprint-2/stretch/count-words.js b/Sprint-2/stretch/count-words.js
index 8e85d19d7..3458e19cc 100644
--- a/Sprint-2/stretch/count-words.js
+++ b/Sprint-2/stretch/count-words.js
@@ -26,3 +26,51 @@
 
 3. Order the results to find out which word is the most common in the input
 */
+
+function countWords(str) {
+  // Split the string into words
+  const words = str.split(/\s+/);
+  
+  // Create an object to hold the word counts
+  const wordCount = {};
+
+  // Loop through each word
+  for (const word of words) {
+    // Normalize the word to lowercase and remove punctuation
+    const cleanWord = word.toLowerCase().replace(/[.,!?]/g, '');
+    
+    // If the word is not in the object, add it with a count of 1
+    if (!wordCount[cleanWord]) {
+      wordCount[cleanWord] = 1;
+    } else {
+      // If it exists, increment the count
+      wordCount[cleanWord]++;
+    }
+  }
+
+  return wordCount;
+}
+
+//function countWords(str) {
+//  const words = str.split(/\s+/);
+//  const counts = {};
+
+//  for (let word of words) {
+//    word = word.toLowerCase().replace(/[.,!?]/g, '');
+//    counts[word] = (counts[word] || 0) + 1;
+//  }
+
+//  return counts;
+// }
+
+// Example usage
+const result = countWords("you and me and you");
+console.log(result); // { you: 2, and: 2, me: 1 }   
+
+console.log(countWords("Hello, hello! How are you? You are great."));
+// { hello: 2, how: 1, are: 2, you: 2, great: 1 }
+console.log(countWords("This is a test. This test is only a test."));
+// { this: 2, is: 3, a: 2, test: 3, only: 1 }
+// Example with punctuation and case insensitivity
+console.log(countWords("Hello, world! Hello, everyone. Hello!"));
+// { hello: 3, world: 1, everyone: 1 }  
\ No newline at end of file
diff --git a/Sprint-2/stretch/mode.js b/Sprint-2/stretch/mode.js
index 3f7609d79..c2bae11ae 100644
--- a/Sprint-2/stretch/mode.js
+++ b/Sprint-2/stretch/mode.js
@@ -8,29 +8,41 @@
 // refactor calculateMode by splitting up the code
 // into smaller functions using the stages above
 
-function calculateMode(list) {
-  // track frequency of each value
-  let freqs = new Map();
+function trackFrequency(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("Input must be an array");
+  }
 
-  for (let num of list) {
+  const freqs = new Map();
+
+  for (const num of list) {
     if (typeof num !== "number") {
       continue;
     }
-
     freqs.set(num, (freqs.get(num) || 0) + 1);
   }
 
-  // Find the value with the highest frequency
+  return freqs;
+}
+
+// Stage 2: Find the value with the highest frequency
+function highestFrequency(freqs) {
   let maxFreq = 0;
   let mode;
-  for (let [num, freq] of freqs) {
+
+  for (const [num, freq] of freqs) {
     if (freq > maxFreq) {
-      mode = num;
       maxFreq = freq;
+      mode = num;
     }
   }
-
   return maxFreq === 0 ? NaN : mode;
 }
 
-module.exports = calculateMode;
+// Main function: combine both stages
+function calculateMode(list) {
+  const freqs = trackFrequency(list);
+  return highestFrequency(freqs);
+}
+
+module.exports = calculateMode;
\ No newline at end of file
diff --git a/Sprint-2/stretch/mode.test.js b/Sprint-2/stretch/mode.test.js
index ca33c28a3..f85c5a127 100644
--- a/Sprint-2/stretch/mode.test.js
+++ b/Sprint-2/stretch/mode.test.js
@@ -29,4 +29,11 @@ describe("calculateMode()", () => {
 
     expect(calculateMode(nums)).toEqual(3);
   });
+
+  test("returns NaN for an empty array", () => {
+    const nums = [];
+
+    expect(calculateMode(nums)).toBeNaN();
+  });
+  
 });
diff --git a/Sprint-2/stretch/till.js b/Sprint-2/stretch/till.js
index 6a08532e7..8e89d8977 100644
--- a/Sprint-2/stretch/till.js
+++ b/Sprint-2/stretch/till.js
@@ -23,9 +23,31 @@ const till = {
 const totalAmount = totalTill(till);
 
 // a) What is the target output when totalTill is called with the till object
+// The target output when totalTill is called with the till object is "£3.16".
+// The current output is "£0.00" because the implementation is incorrect.
+
 
 // b) Why do we need to use Object.entries inside the for...of loop in this function?
+// We need to use Object.entries to iterate over the key-value pairs of the till object.
+// It allows us to access both the coin (key) and its quantity (value) in each iteration.
+// e.g. Object.entries(till) returns [["1p", 10], ["5p", 6], ["50p", 4], ["20p", 10]].
+
 
 // c) What does coin * quantity evaluate to inside the for...of loop?
+// Inside the for...of loop, coin * quantity evaluates to the total value of that type of coin in pence.
+// For example, if coin is "1p" and quantity is 10, it evaluates
+// to 1 * 10 = 10 pence.
+// It evaluates to the total value of that type of coin in pence.
+
 
 // d) Write a test for this function to check it works and then fix the implementation of totalTill
+function totalTill(till) {
+  let total = 0;
+
+  for (const [coin, quantity] of Object.entries(till)) {
+    const coinValue = parseInt(coin.replace('p', '')); // Convert coin string to number
+    total += coinValue * quantity; // Calculate total in pence
+  }
+
+  return `£${(total / 100).toFixed(2)}`; // Return total in pounds formatted to two decimal places
+}