diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..38a2812de 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,4 +1,6 @@
 // Predict and explain first...
+// I predict that this code won't work because the house number is accessed using the wrong syntax.
+// The house number is a property of the address object, so it should be accessed using dot notation.
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +14,4 @@ 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..a26a6aed1 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,4 +1,5 @@
 // Predict and explain first...
+// I predict it will throw an error because the for...of loop is trying to iterate over an object, object is not iterable.
 
 // 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 +12,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..626870b63 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-
+// I predict that this code wont work because the way the ingredients  property is being accessed is wrong.
+// The ingredients property is an array, so it should be accessed using dot notation and need a method to print all elements.
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
 // How can you fix it?
@@ -11,5 +12,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients:
+${recipe.ingredients.join("\n  ")}`);
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..6f79ce219 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,5 @@
-function contains() {}
+function contains(obj, prop) {
+  return obj.hasOwnProperty(prop);
+}
 
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..3ec8d224f 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -11,25 +11,44 @@ E.g. contains({a: 1, b: 2}, 'c') // returns false
 as the object doesn't contains a key of 'c'
 */
 
-// Acceptance criteria:
-
-// 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
-
-// Given an empty object
-// When passed to contains
-// Then it should return false
-test.todo("contains on empty object returns false");
-
-// Given an object with properties
-// When passed to contains with an existing property name
-// Then it should return true
-
-// Given an object with properties
-// When passed to contains with a non-existent property name
-// Then it should return false
-
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
+describe("contains", () => {
+  // Acceptance criteria:
+
+  // 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")).toEqual(true);
+  });
+
+  // Given an empty object
+  // When passed to contains
+  // Then it should return false
+  test("contains returns false for empty object", () => {
+    const obj = {};
+    expect(contains(obj, "a")).toEqual(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", () => {
+    const obj = { a: 1, b: 2 };
+    expect(contains(obj, "a")).toEqual(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", () => {
+    const obj = { a: 1, b: 2 };
+    expect(contains(obj, "c")).toEqual(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, "a")).toEqual(false);
+  });
+});
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..c05e11850 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,11 @@
-function createLookup() {
+function createLookup(countryCurrencyPairs) {
   // implementation here
+
+  const lookup = {};
+  for (const [key, value] of countryCurrencyPairs) {
+    lookup[key] = value;
+  }
+  return lookup;
 }
 
 module.exports = createLookup;
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..192349ab2 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,7 +1,5 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
@@ -33,3 +31,21 @@ It should return:
    'CA': 'CAD'
  }
 */
+
+describe("createLookup", () => {
+  test("creates a country currency code lookup for multiple codes", () => {
+    const countryCurrencyPairs = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+      ["GB", "GBP"],
+    ];
+
+    const expectedLookup = {
+      US: "USD",
+      CA: "CAD",
+      GB: "GBP",
+    };
+
+    expect(createLookup(countryCurrencyPairs)).toEqual(expectedLookup);
+  });
+});
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..bf741f2c5 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -1,13 +1,23 @@
 function parseQueryString(queryString) {
   const queryParams = {};
+
+  if (queryString.startsWith("?")) {
+    queryString = queryString.slice(1);
+  }
+
   if (queryString.length === 0) {
     return queryParams;
   }
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    if (pair === "") {
+      continue;
+    }
+
+    const [key, ...value] = pair.split("=");
+
+    queryParams[key] = value.join("=");
   }
 
   return queryParams;
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..142e2cbdf 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,10 +3,31 @@
 // Below is one test case for an edge case the implementation doesn't handle well.
 // Fix the implementation for this test, and try to think of as many other edge cases as possible - write tests and fix those too.
 
-const parseQueryString = require("./querystring.js")
+const parseQueryString = require("./querystring.js");
 
 test("parses querystring values containing =", () => {
   expect(parseQueryString("equation=x=y+1")).toEqual({
-    "equation": "x=y+1",
+    equation: "x=y+1",
+  });
+});
+
+test("ignores a leading question mark", () => {
+  expect(parseQueryString("?name=zadie&age=40")).toEqual({
+    name: "zadie",
+    age: "40",
+  });
+});
+
+test("handles empty pairs caused by stray ampersands", () => {
+  expect(parseQueryString("a=1&&&b=2&")).toEqual({
+    a: "1",
+    b: "2",
+  });
+});
+
+test("handles keys that have no values", () => {
+  expect(parseQueryString("active&sort=desc")).toEqual({
+    active: "",
+    sort: "desc",
   });
 });
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..b1d689f99 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,19 @@
-function tally() {}
+function tally(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("Input must be an array");
+  }
+
+  const counts = {};
+
+  for (const item of list) {
+    if (counts[item]) {
+      counts[item] = counts[item] + 1;
+    } else {
+      counts[item] = 1;
+    }
+  }
+
+  return counts;
+}
 
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..14af20b71 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -19,16 +19,32 @@ const tally = require("./tally.js");
 // Given a function called tally
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
-
+test("tally counts the frequency of items in an array", () => {
+  const input = ["a", "a", "b", "c"];
+  const expectedOutput = { a: 2, b: 1, c: 1 };
+  expect(tally(input)).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 on an empty array returns an empty object", () => {
+  const input = [];
+  const expectedOutput = {};
+  expect(tally(input)).toEqual(expectedOutput);
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("tally counts duplicate items correctly", () => {
+  const input = ["x", "y", "x", "z", "y", "x"];
+  const expectedOutput = { x: 3, y: 2, z: 1 };
+  expect(tally(input)).toEqual(expectedOutput);
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("tally throws an error for invalid input", () => {
+  expect(() => tally("not an array")).toThrow("Input must be an array");
+});
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..8fb05c1aa 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -6,24 +6,39 @@
 
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
-function invert(obj) {
-  const invertedObj = {};
+// function invert(obj) {
+//   const invertedObj = {};
 
-  for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
-  }
+//   for (const [key, value] of Object.entries(obj)) {
+//     invertedObj.key = value;
+//   }
 
-  return invertedObj;
-}
+//   return invertedObj;
+// }
 
 // a) What is the current return value when invert is called with { a : 1 }
+// my guess is that it will return { key: 1 } because the code is setting the property "key" on the invertedObj to the value of 1.
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// { key : 2 } because the loop will overwrite the "key" property with the value of 2 after processing the second key-value pair.
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// target output: {1: "a", 2: "b"}
+
+// d) What does Object.entries return? Why is it needed in this program?
+// Object.entries returns an array of arrays from an object. It's needed to iterate over each property in the object.
 
-// c) What does Object.entries return? Why is it needed in this program?
+// e) Explain why the current return value is different from the target output
+// because the current implementation is using key as a literal property name instead of using the value of the variable key with bracket notation.
+// f) Fix the implementation of invert (and write tests to prove it's fixed!)
+function invert(obj) {
+  const invertedObj = {};
 
-// d) Explain why the current return value is different from the target output
+  for (const [key, value] of Object.entries(obj)) {
+    invertedObj[value] = key;
+  }
+
+  return invertedObj;
+}
 
-// e) Fix the implementation of invert (and write tests to prove it's fixed!)
+module.exports = invert;
diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
new file mode 100644
index 000000000..17f5cb5b2
--- /dev/null
+++ b/Sprint-2/interpret/invert.test.js
@@ -0,0 +1,25 @@
+const invert = require("./invert");
+
+test("invert returns an object with keys and values swapped, simple case", () => {
+  const input = { a: 1 };
+  const expectedOutput = { 1: "a" };
+  expect(invert(input)).toEqual(expectedOutput);
+});
+
+test("invert returns an object with keys and values swapped, multiple pairs", () => {
+  const input = { a: 1, b: 2 };
+  const expectedOutput = { 1: "a", 2: "b" };
+  expect(invert(input)).toEqual(expectedOutput);
+});
+
+test("invert handles empty objects", () => {
+  const input = {};
+  const expectedOutput = {};
+  expect(invert(input)).toEqual(expectedOutput);
+});
+
+test("invert handles non-string values", () => {
+  const input = { x: true, y: null };
+  const expectedOutput = { true: "x", null: "y" };
+  expect(invert(input)).toEqual(expectedOutput);
+});
diff --git a/Sprint-2/stretch/count-words.js b/Sprint-2/stretch/count-words.js
index 8e85d19d7..01a1749f6 100644
--- a/Sprint-2/stretch/count-words.js
+++ b/Sprint-2/stretch/count-words.js
@@ -26,3 +26,31 @@
 
 3. Order the results to find out which word is the most common in the input
 */
+
+function countWords(str) {
+  const wordCounts = {};
+
+  const cleanedStr = str
+    .replace(/[.,!?&@?]+/g, "")
+    .toLowerCase()
+    .trim();
+
+  const words = cleanedStr.split(/\s+/);
+
+  for (const word of words) {
+    if (word === "") {
+      continue;
+    }
+    if (wordCounts[word]) {
+      wordCounts[word] += 1;
+    } else {
+      wordCounts[word] = 1;
+    }
+  }
+
+  return wordCounts;
+}
+
+console.log(countWords("you a?nd? me ??and&@?you"));
+
+module.exports = countWords;
diff --git a/Sprint-2/stretch/count-words.test.js b/Sprint-2/stretch/count-words.test.js
new file mode 100644
index 000000000..51821ec7e
--- /dev/null
+++ b/Sprint-2/stretch/count-words.test.js
@@ -0,0 +1,37 @@
+const countWords = require("./count-words");
+
+test("counts the number of times each word appears in a string", () => {
+  const input = "you and me and you";
+  const expectedOutput = { you: 2, and: 2, me: 1 };
+  expect(countWords(input)).toEqual(expectedOutput);
+});
+
+test("handles punctuation and case sensitivity", () => {
+  const input = "Hello, hello! How are you? You look well.";
+  const expectedOutput = { hello: 2, how: 1, are: 1, you: 2, look: 1, well: 1 };
+  expect(countWords(input)).toEqual(expectedOutput);
+});
+
+test("handles an empty string", () => {
+  const input = "";
+  const expectedOutput = {};
+  expect(countWords(input)).toEqual(expectedOutput);
+});
+
+test("handles a string with only punctuation", () => {
+  const input = "!!!,,,???";
+  const expectedOutput = {};
+  expect(countWords(input)).toEqual(expectedOutput);
+});
+
+test("handles a string with multiple spaces", () => {
+  const input = "   you   and   me   ";
+  const expectedOutput = { you: 1, and: 1, me: 1 };
+  expect(countWords(input)).toEqual(expectedOutput);
+});
+
+test("handles a string with numbers and special characters", () => {
+  const input = "hello123 world! @hello";
+  const expectedOutput = { hello123: 1, world: 1, hello: 1 };
+  expect(countWords(input)).toEqual(expectedOutput);
+});