diff --git a/Sprint-1/1-key-exercises/1-count.js b/Sprint-1/1-key-exercises/1-count.js
index 117bcb2b6..6670bfb61 100644
--- a/Sprint-1/1-key-exercises/1-count.js
+++ b/Sprint-1/1-key-exercises/1-count.js
@@ -4,3 +4,6 @@ count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing
+
+//In the Line 3 we can see that using the equal symbol '=' a new value is been assigned to the variable 'count'. 
+// Specifically the new value assigned is the previous value plus 1. Due to the previous value was 0 now is 1. 
\ No newline at end of file
diff --git a/Sprint-1/1-key-exercises/2-initials.js b/Sprint-1/1-key-exercises/2-initials.js
index 47561f617..0ad95d2df 100644
--- a/Sprint-1/1-key-exercises/2-initials.js
+++ b/Sprint-1/1-key-exercises/2-initials.js
@@ -5,7 +5,8 @@ let lastName = "Johnson";
 // Declare a variable called initials that stores the first character of each string.
 // This should produce the string "CKJ", but you must not write the characters C, K, or J in the code of your solution.
 
-let initials = ``;
+let initials = firstName[0] + middleName[0] + lastName[0];
+console.log(initials) 
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 
diff --git a/Sprint-1/1-key-exercises/3-paths.js b/Sprint-1/1-key-exercises/3-paths.js
index ab90ebb28..38d61bb24 100644
--- a/Sprint-1/1-key-exercises/3-paths.js
+++ b/Sprint-1/1-key-exercises/3-paths.js
@@ -17,7 +17,8 @@ console.log(`The base part of ${filePath} is ${base}`);
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const dir = filePath.slice(1,lastSlashIndex);
+const ext = filePath.slice(filePath.lastIndexOf(".") + 1);
+console.log('The dir part of the filePath variable is "'+ dir +'", the ext part is: "' + ext + '".');
 
 // https://www.google.com/search?q=slice+mdn
\ No newline at end of file
diff --git a/Sprint-1/1-key-exercises/4-random.js b/Sprint-1/1-key-exercises/4-random.js
index 292f83aab..b57f573b1 100644
--- a/Sprint-1/1-key-exercises/4-random.js
+++ b/Sprint-1/1-key-exercises/4-random.js
@@ -2,8 +2,18 @@ const minimum = 1;
 const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
-
+console.log(num)
 // In this exercise, you will need to work out what num represents?
 // Try breaking down the expression and using documentation to explain what it means
 // It will help to think about the order in which expressions are evaluated
 // Try logging the value of num and running the program several times to build an idea of what the program is doing
+
+// The variable num represents a integer number obtained as a result of a math operation including 
+// the math functions floor and random, to obtain a random number between 1 and 100.
+// Math.random(): generates an random decimal number. Math.floor(): rounds a number down to the nearest integer.
+
+// The order of the expressions: 
+// 1. The arithmetic operations  100 (maximum) - 1 (minimum) + 1
+// 2. A random decimal number between 0 and 1 (no included) is generated by the random function and multiplied by 100
+// 3. The number is rounded with the floor function
+// 4. Is added the number + 1 to permit the possibility of to obtain 1 or 100
diff --git a/Sprint-1/2-mandatory-errors/0.js b/Sprint-1/2-mandatory-errors/0.js
index cf6c5039f..60e7fb92c 100644
--- a/Sprint-1/2-mandatory-errors/0.js
+++ b/Sprint-1/2-mandatory-errors/0.js
@@ -1,2 +1,14 @@
 This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
\ No newline at end of file
+We don't want the computer to run these 2 lines - how can we solve this problem?
+
+/* To avoid that the computer run lines on our code, we use characters to make them comments.
+ In Javascript we can use '//' for simple lines or '/* comment * /' for paragraphs: 
+ */ 
+
+//This is just an instruction for the first activity - but it is just for human consumption
+//We don't want the computer to run these 2 lines - how can we solve this problem?
+
+/*
+This is just an instruction for the first activity - but it is just for human consumption
+We don't want the computer to run these 2 lines - how can we solve this problem?
+*/
diff --git a/Sprint-1/2-mandatory-errors/1.js b/Sprint-1/2-mandatory-errors/1.js
index 7a43cbea7..bd6a00268 100644
--- a/Sprint-1/2-mandatory-errors/1.js
+++ b/Sprint-1/2-mandatory-errors/1.js
@@ -1,4 +1,6 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+// The age variable was declared as const; as a result, it can't be reassigned. 
+// AS solution the variable was declared using 'let'.
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/2.js b/Sprint-1/2-mandatory-errors/2.js
index e09b89831..147dfd94e 100644
--- a/Sprint-1/2-mandatory-errors/2.js
+++ b/Sprint-1/2-mandatory-errors/2.js
@@ -1,5 +1,8 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+// When the message was tried to be printed the system couldn't access to 'cityOfBirth'
+// The declaration of the const cityOfBirth must be done before.
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/3.js b/Sprint-1/2-mandatory-errors/3.js
index ec101884d..094b9b373 100644
--- a/Sprint-1/2-mandatory-errors/3.js
+++ b/Sprint-1/2-mandatory-errors/3.js
@@ -1,9 +1,16 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
-
+const last4Digits = String(cardNumber).slice(-4);
+console.log(last4Digits)
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
 // Before running the code, make and explain a prediction about why the code won't work
 // Then run the code and see what error it gives.
 // Consider: Why does it give this error? Is this what I predicted? If not, what's different?
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+
+/*
+On the first sight I thought that -4 was not a valid value for the slice function. Then I notice that slice works for strings.
+Running Error: "TypeError: cardNumber.slice is not a function"
+The message doesn't mention the value for slice must be a string.
+to extract a part of a number, it must be treated as a string: String(cardNumber)
+*/
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/4.js b/Sprint-1/2-mandatory-errors/4.js
index 21dad8c5d..3d46dc35c 100644
--- a/Sprint-1/2-mandatory-errors/4.js
+++ b/Sprint-1/2-mandatory-errors/4.js
@@ -1,2 +1,6 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
\ No newline at end of file
+const hourClockTime12 = "20:53";
+const hourClockTime24 = "08:53";
+
+/* 
+The variables on javascript must be declared starting with a letter.
+*/
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/1-percentage-change.js b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
index e24ecb8e1..3ba64c2fa 100644
--- a/Sprint-1/3-mandatory-interpret/1-percentage-change.js
+++ b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
@@ -2,7 +2,7 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," , ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -12,11 +12,12 @@ console.log(`The percentage change is ${percentageChange}`);
 // Read the code and then answer the questions below
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
-
+// 4, 4, 5, 5, 10 total 5 function calls. 
 // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
-
+// line 5 the replaceAll function requires two parameters, which must be separated by coma. 
 // c) Identify all the lines that are variable reassignment statements
-
+// There are variable reassignments statements on the lines: 4 and 5
 // d) Identify all the lines that are variable declarations
-
+// There are variable declarations in the lines: 1, 2, 7 and 8
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// The carPrice include the character , to made it a number, the comma is replaced by "" (nothing) and use the function Number()
diff --git a/Sprint-1/3-mandatory-interpret/2-time-format.js b/Sprint-1/3-mandatory-interpret/2-time-format.js
index 47d239558..a8a6d0441 100644
--- a/Sprint-1/3-mandatory-interpret/2-time-format.js
+++ b/Sprint-1/3-mandatory-interpret/2-time-format.js
@@ -12,14 +12,18 @@ console.log(result);
 // For the piece of code above, read the code and then answer the following questions
 
 // a) How many variable declarations are there in this program?
-
+//   Lines: 1, 3, 4, 9. Total 4
 // b) How many function calls are there?
-
+//   One, in the line 10
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
-
+//   Obtain as a result the reminder of the division of movieLength between 60
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
-
+//   The expression 
+//   find difference of the movieLength minus the remainingSeconds to obtain the amount of seconds exactly divisible by 60
+//   do the division to obtain the total in minutes, which is the value assigned to totalMinutes
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
-
+//    The variable result represents the duration of the film, expressed with the format: HH:MM:SS
+//    A better name could be movieDuration.
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+//    It works for all values of movieLength. With long names, the number of hours can be hundreds.
diff --git a/Sprint-1/3-mandatory-interpret/3-to-pounds.js b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
index 60c9ace69..33a67a606 100644
--- a/Sprint-1/3-mandatory-interpret/3-to-pounds.js
+++ b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
@@ -24,4 +24,22 @@ console.log(`£${pounds}.${pence}`);
 // Try and describe the purpose / rationale behind each step
 
 // To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 1. Const penceString = "399p": initializes a string variable with the value "399p"
+// 2. Empty
+// 3. Const penceStringWithoutTrailingP initializes and assigned the value of function penceString.substring()
+// 4. First position of string
+// 5. End position of string taken with the length of the string minus the last character p using -1
+// 6. Close function penceString.substring
+// 7. Empty
+// 8. Const paddedPenceNumberString initializes and assigned the value of function penceStringWithoutTrailingP.padStart(
+// padding the string with "0" until it reaches the length 3
+// 9. Const pounds initializes and assigned the value of function paddedPenceNumberString.substring(
+//10. the number is extracted from the first character 
+//11. to the length of the string except the last two characters.
+//12. End of function
+//13. Empty
+//14. Const pence initializes and assigned the value of function paddedPenceNumberString.substring()
+//15. using the length of the paddedPenceNumberString minus 2 for decimal (pens) values.
+//16. Padding with 00 until two characters
+//17. Empty
+//18. Print on console the value using the characters £ representing pounds and dot separating pens.
\ No newline at end of file
diff --git a/Sprint-1/4-stretch-explore/chrome.md b/Sprint-1/4-stretch-explore/chrome.md
index e7dd5feaf..c9589680b 100644
--- a/Sprint-1/4-stretch-explore/chrome.md
+++ b/Sprint-1/4-stretch-explore/chrome.md
@@ -11,8 +11,13 @@ In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?
+Calling the alert() function causes a pop-up dialog box which appear in the browser
+displaying the message "Hello world!" and an OK button.
 
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
 What effect does calling the `prompt` function have?
+Invoking the 'prompt' function causes an input pup-up dialog in the web browser displaying the message 'What is your name?' and waiting for information from the user.
+
 What is the return value of `prompt`?
+The return value that was provided by the user.
diff --git a/Sprint-1/4-stretch-explore/objects.md b/Sprint-1/4-stretch-explore/objects.md
index 0216dee56..91e3e6825 100644
--- a/Sprint-1/4-stretch-explore/objects.md
+++ b/Sprint-1/4-stretch-explore/objects.md
@@ -5,12 +5,19 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
+f Log() {[native code]}
 
 Now enter just `console` in the Console, what output do you get back?
+console {debug: f, error: f, info: f, log, f, warn: f,...}
+a full detailed list of methods or functions which can be expanded in the console to see al its properties.
 
 Try also entering `typeof console`
+'object'
 
 Answer the following questions:
 
 What does `console` store?
+the console stores a collection of functions that provide different functionalities.
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+The dot connect the main function console to sub-functions which are part of the shorthand. The '.' operator allow access to the properties that belong to console.