diff --git a/Sprint-1/fix/median.js b/Sprint-1/fix/median.js
index 5c5b796e1..341149049 100644
--- a/Sprint-1/fix/median.js
+++ b/Sprint-1/fix/median.js
@@ -6,9 +6,23 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+  if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+  for (const item of list) {
+    if (typeof item !== "number") {
+      throw new Error("calculateMedian requires an array of numbers");
+    }
+  }
+  let arr = [...list];
+  arr.sort((a, b) => a - b);
+  const middleIndex = Math.floor(arr.length / 2);
+  if (arr.length % 2 === 0) {
+    return (arr[middleIndex - 1] + arr[middleIndex]) / 2;
+  }
+  return arr[middleIndex];
 }
-
 module.exports = calculateMedian;
diff --git a/Sprint-1/implement/dedupe.js b/Sprint-1/implement/dedupe.js
index 781e8718a..9802cae9e 100644
--- a/Sprint-1/implement/dedupe.js
+++ b/Sprint-1/implement/dedupe.js
@@ -1 +1,5 @@
-function dedupe() {}
+function dedupe(a) {
+    return (a.length === 0) ? [] : [...new Set(a)]
+}
+
+module.exports = dedupe; 
\ No newline at end of file
diff --git a/Sprint-1/implement/dedupe.test.js b/Sprint-1/implement/dedupe.test.js
index d7c8e3d8e..ad3a9b09f 100644
--- a/Sprint-1/implement/dedupe.test.js
+++ b/Sprint-1/implement/dedupe.test.js
@@ -16,13 +16,33 @@ E.g. dedupe([1, 2, 1]) returns [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+test("given an empty array, it returns an empty array", () => {
+    const arr = [];
+    const actual = dedupe(arr);
+    expect(actual).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("array with no dupes returns original array", () => {
+    const arr = [1, 2, 3];
+    const actual = dedupe(arr);
+    expect(actual).toEqual([1, 2, 3]);
+})
 
 // Given an array of strings or numbers
 // When passed to the dedupe function
 // Then it should return a new array with duplicates removed while preserving the 
 // first occurrence of each element from the original array.
+test("array with dupe numbers returns a copy with no dupes", () => {
+    const arr = [1, 2, 2, 3];
+    const actual = dedupe(arr);
+    expect(actual).toEqual([1, 2, 3]);
+})
+
+test("array with dupe words returns a copy with no dupes", () => {
+    const arr = ['hi', 'bye', 'bye', 'sigh'];
+    const actual = dedupe(arr);
+    expect(actual).toEqual(['hi', 'bye', 'sigh']);
+})
diff --git a/Sprint-1/implement/describe-median.js b/Sprint-1/implement/describe-median.js
index 3381cfc0a..ca4436819 100644
--- a/Sprint-1/implement/describe-median.js
+++ b/Sprint-1/implement/describe-median.js
@@ -20,6 +20,14 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) {
+  try {
+    const median = calculateMedian(list);
+    return `The median is ${median}`
+  }
+  catch (error) {
+    return `Could not calculate a median: ${error.message}`
+  }
+}
 
 module.exports = describeMedian;
diff --git a/Sprint-1/implement/describe-median.test.js b/Sprint-1/implement/describe-median.test.js
index e7d18a264..32d6801a1 100644
--- a/Sprint-1/implement/describe-median.test.js
+++ b/Sprint-1/implement/describe-median.test.js
@@ -21,12 +21,26 @@ const describeMedian = require("./describe-median.js");
 // When passed to describeMedian
 // Then it should return "The median is " followed by the median
 // Delete this test.todo and replace it with a test.
-test.todo('given [1, 2, 3], returns "The median is 2"');
+test('given [1, 2, 3], returns "The median is 2"', () => {
+    const input = [1, 2, 3];
+    const result = describeMedian(input);
+    expect(result).toEqual("The median is 2");
+});
 
 // Given an empty array
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
+test('given [], returns "Could not calculate a median: calculateMedian requires a non-empty array"', () => {
+    const input = [];
+    const result = describeMedian(input);
+    expect(result).toEqual("Could not calculate a median: calculateMedian requires a non-empty array");
+});
 
 // Given something that isn't an array of numbers, e.g. "banana"
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires an array of numbers"
+test('given "banana", returns "Could not calculate a median: calculateMedian requires an array of numbers"', () => {
+    const input = 'banana';
+    const result = describeMedian(input);
+    expect(result).toEqual("Could not calculate a median: calculateMedian requires an array of numbers");
+});
\ No newline at end of file
diff --git a/Sprint-1/implement/max.js b/Sprint-1/implement/max.js
index 6dd76378e..d9fe8b938 100644
--- a/Sprint-1/implement/max.js
+++ b/Sprint-1/implement/max.js
@@ -1,4 +1,13 @@
 function findMax(elements) {
+    if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+    }
+    for (const item of elements) {
+        if (typeof item !== "number") {
+        throw new Error("findMax requires an array of numbers");
+        }
+    }
+    return Math.max(...elements)
 }
 
 module.exports = findMax;
diff --git a/Sprint-1/implement/max.test.js b/Sprint-1/implement/max.test.js
index ff3fbb5e5..427bf7fd5 100644
--- a/Sprint-1/implement/max.test.js
+++ b/Sprint-1/implement/max.test.js
@@ -16,28 +16,61 @@ const findMax = require("./max.js");
 // When passed to the max function
 // Then it should return -Infinity
 // Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+test("given an empty array, returns -Infinity", () => {
+    const input = [];
+    const result = findMax(input);
+    expect(result).toEqual(-Infinity)
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("given [3], returns 3", () => {
+    const input = [3];
+    const result = findMax(input);
+    expect(result).toEqual(3)
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("given [3, -2, 4, -10], returns 4", () => {
+    const input = [3, -2, 4, -10];
+    const result = findMax(input);
+    expect(result).toEqual(4)
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given [-3, -2, -4, -10], returns -2", () => {
+    const input = [-3, -2, -4, -10];
+    const result = findMax(input);
+    expect(result).toEqual(-2)
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
-
+test("given [0.3, 0.22, 0.64, 0.1], returns 0.64", () => {
+    const input = [0.3, 0.22, 0.64, 0.1];
+    const result = findMax(input);
+    expect(result).toEqual(0.64)
+});
 // Given an array containing a value that isn't a number
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
+test('given ["hi", 2, 3], throws Error:"findMax requires an array of numbers"', () => {
+    const input = ['hi', 2, 3];
+    //const result = findMax(input);
+    expect(() => findMax(input)).toThrow("findMax requires an array of numbers")
+});
 
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
+test('given "big snake", throws Error:"findMax requires an array of numbers"', () => {
+    const input = "big snake";
+    //const result = findMax(input);
+    expect(() => findMax(input)).toThrow("findMax requires an array of numbers")
+});
\ No newline at end of file
diff --git a/Sprint-1/implement/mean.js b/Sprint-1/implement/mean.js
index 36909ea1f..930a78a78 100644
--- a/Sprint-1/implement/mean.js
+++ b/Sprint-1/implement/mean.js
@@ -1,3 +1,24 @@
-function calculateMean(list) {}
+function calculateMean(list) {
+    if (!Array.isArray(list)){
+        throw new Error("calculateMean requires an array of numbers");
+    }
+    if (list.length === 0){
+        throw new Error("calculateMean requires a non-empty array");
+    }
+    for (const item of list) {
+        if (typeof item !== "number"){
+            throw new Error("calculateMean requires an array of numbers");
+        }
+    };
+    let sum = 0;
+    for (let i=0; i<list.length ; i++) {
+        sum += list[i];
+    };
+    return sum/(list.length);
+}
 
 module.exports = calculateMean;
+
+/*
+mean = sum / length -1
+*/
\ No newline at end of file
diff --git a/Sprint-1/implement/mean.test.js b/Sprint-1/implement/mean.test.js
index 847b88676..b68fb0309 100644
--- a/Sprint-1/implement/mean.test.js
+++ b/Sprint-1/implement/mean.test.js
@@ -23,28 +23,56 @@ const calculateMean = require("./mean.js");
 // When passed to calculateMean
 // Then it should return their mean
 // Delete this test.todo and replace it with a test.
-test.todo("given [1, 2, 6], returns 3");
+test("given [1, 2, 6], returns 3", () => {
+    const input = [1, 2, 6];
+    const result = calculateMean(input);
+    expect(result).toEqual(3);
+});
 
 // Given an array with a single number
 // When passed to calculateMean
 // Then it should return that number
+test("given [69], returns 69", () => {
+    const input = [69];
+    const result = calculateMean(input);
+    expect(result).toEqual(69);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
+test("given [-1, 0.2, 6], returns 1.73", () => {
+    const input = [-1, 0.2, 6];
+    const result = calculateMean(input);
+    expect(result).toEqual(1.7333333333333334);
+});
 
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
+test('given [], throw Error("calculateMean requires a non-empty array"', () => {
+    const input = [];
+    expect(() => calculateMean(input)).toThrow("calculateMean requires a non-empty array");
+});
 
 // Given a value that isn't an array, e.g. "banana", 42, null or {}
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+test('given "catfish cabin", throw Error("calculateMean requires an array of numbers"', () => {
+    const input = "catfish cabin";
+    expect(() => calculateMean(input)).toThrow("calculateMean requires an array of numbers");
+});
 
 // Given no argument at all
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
-
+test('given "catfish cabin", throw Error("calculateMean requires an array of numbers"', () => {
+    expect(() => calculateMean()).toThrow("calculateMean requires an array of numbers");
+});
 // Given an array containing a non-number value, e.g. [1, "2", 3]
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+test('given [1, "2", 3], throw Error("calculateMean requires an array of numbers"', () => {
+    const input = [1, "2", 3];
+    expect(() => calculateMean(input)).toThrow("calculateMean requires an array of numbers");
+});
\ No newline at end of file
diff --git a/Sprint-1/implement/sum.js b/Sprint-1/implement/sum.js
index 9062aafe3..864633a27 100644
--- a/Sprint-1/implement/sum.js
+++ b/Sprint-1/implement/sum.js
@@ -1,4 +1,17 @@
 function sum(elements) {
+    if (!Array.isArray(elements)){
+        throw new Error("sum requires an array of numbers");
+    }
+    for (const item of elements){
+        if (typeof item !== 'number'){
+            throw new Error("sum requires an array of numbers");
+        }
+    }
+    let result = 0;
+    for (let i = 0; i < elements.length; i++){
+        result += elements[i]
+    }
+    return result
 }
 
 module.exports = sum;
diff --git a/Sprint-1/implement/sum.test.js b/Sprint-1/implement/sum.test.js
index a288e0f0a..7ceae5eef 100644
--- a/Sprint-1/implement/sum.test.js
+++ b/Sprint-1/implement/sum.test.js
@@ -13,24 +13,51 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("given an empty array, returns 0", () => {
+    const input = [];
+    result = sum(input);
+    expect(result).toEqual(0);
+})
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given [12], returns 12", () => {
+    const input = [12];
+    result = sum(input);
+    expect(result).toEqual(12);
+})
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given [-1, -2, -3], returns -6", () => {
+    const input = [-1, -2, -3];
+    result = sum(input);
+    expect(result).toEqual(-6);
+})
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given [0.1, 0.2, 0.34], returns 0.6000000000000001", () => {
+    const input = [0.1, 0.2, 0.3];
+    result = sum(input);
+    expect(result).toEqual(0.6000000000000001);
+})
 
 // Given an array containing a value that isn't a number
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
+test("given ['grace', 'peter', 'steph', 'ruth', 'richie'], throw Error:'sum requires an array of numbers'", () => {
+    const input = ['grace', 'peter', 'steph', 'ruth', 'richie'];
+    expect(() => sum(input)).toThrow("sum requires an array of numbers");
+});
 
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
+test("given 'stink stank stunk', throw Error:'sum requires an array of numbers'", () => {
+    const input = 'stink stank stunk';
+    expect(() => sum(input)).toThrow("sum requires an array of numbers");
+})
diff --git a/Sprint-1/refactor/includes.js b/Sprint-1/refactor/includes.js
index 29dad81f0..36d9dfb1f 100644
--- a/Sprint-1/refactor/includes.js
+++ b/Sprint-1/refactor/includes.js
@@ -1,12 +1,11 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
-    if (element === target) {
+  for (item of list) {
+    if (target === item)
       return true;
     }
-  }
+  
   return false;
 }