Updates after QA

en/meta.yml

@@ -19,18 +19,16 @@ last_tested: 2017-01-01
 steps:
 - title: What you will make
 - title: The Caesar cipher
-- title: Use a Caesar cipher
-  challenge: true
-  completion:
-  - engaged
 - title: Encrypting letters
   completion:
-  - internal
+  - engaged
 - title: Variable keys
 - title: Encrypting entire messages
+  completion:
+  - internal
 - title: Extra characters
   completion:
   - external
-- title: Encrypting and decrypting messages
+- title: Challenge
   challenge: true
 - title: What can you do now?

en/step_1.md

@@ -1,7 +1,11 @@
 ## What you will make
 
-In this project, you'll learn how to make your own encryption program, to send and receive secret messages with a friend. 
+Create your own encryption program, to send and receive secret messages with a friend. 
 
-<iframe src="https://editor.raspberrypi.org/en/embed/viewer/secret-messages-complete" width="600" height="400" frameborder="0" marginwidth="0" marginheight="0" allowfullscreen> </iframe>
+### Try it!
+
+Press **Run** and enter a key (number) when prompted.
 
-If you need to print this project, please use the [Printer friendly version](https://projects.raspberrypi.org/en/projects/secret-messages/print).
+Then enter a message to encrypt with your chosen key.
+
+<iframe src="https://editor.raspberrypi.org/en/embed/viewer/secret-messages-complete" width="600" height="400" frameborder="0" marginwidth="0" marginheight="0" allowfullscreen> </iframe>

en/step_2.md

@@ -22,10 +22,24 @@ To make a secret encrypted letter from a normal one, you need to have a secret k
 
 You could use the number 3 as the key (but you can use any number you like).
 
-To __encrypt__ the letter 'a', you just move 3 letters clockwise, which will give you the letter 'd':
+--- task ---
+
+Choose your key.
+
+--- /task ---
+
+If you have chosen '3' as your key, you can __encrypt__ the letter 'a' by moving 3 letters clockwise, which will give you the letter 'd':
+
+--- task ---
+
+Encrypt the letter 'a' with your key.
 
 ![screenshot](images/messages-wheel-eg.png)
 
+--- /task ---
+
+--- task ---
+
 Use what you've learnt to encrypt an entire word. 
 
 For example, 'hello' encrypted is 'khoor'. 
@@ -36,6 +50,8 @@ For example, 'hello' encrypted is 'khoor'.
 	+ l + 3 = __o__
 	+ o + 3 = __r__
 
+--- /task ---
+
 Getting text back to normal is called __decryption__. To decrypt a word, just subtract the key instead of adding it:
 
 	+ k - 3 = __h__

en/step_3.md

@@ -1,5 +1,300 @@
-## Use a Caesar cipher
+## Encrypting letters
 
-Can you send a secret word to a friend? You'll both need to agree on a secret key before you start.
+Write a Python program to encrypt a single character.
 
-You could even send entire sentences to each other!
+--- task ---
+
+Open the [Secret Messages starter project](https://editor.raspberrypi.org/en/projects/secret-messages-starter){:target="_blank"}.
+
+--- /task ---
+
+--- task ---
+
+Instead of drawing the alphabet in a circle, write it out as an `alphabet` variable.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 1
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+--- /code ---
+
+--- /task ---
+
+Each letter of the alphabet has a position, starting at position 0. So the letter 'a' is at position 0 of the alphabet, and 'c' is at position 2.
+
+--- task ---
+
+Output a letter from your `alphabet` variable by printing the letter at the position in square brackets.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 2-4
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+print(alphabet[0])
+print(alphabet[6])
+print(alphabet[19])
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+**Test:** Click the **Run** button. 
+
+You can delete the `print` statements once you've tried this out.
+
+--- /task ---
+
+--- task ---
+
+Store the secret `key` in a variable.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 2
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+Ask the user for a single letter (called a `character`) to encrypt.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 4
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+Find the `position` of the `character`.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 6
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+You can test the stored `position` by printing it. For example, that character 'e' is at position 4 in the alphabet.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 7
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+print(position)
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+**Test:** Click the **Run** button. 
+
+You should see the position in the alphabet of the character you entered.
+
+--- /task ---
+
+--- task ---
+
+To encrypt the `character`, you should add the `key` to the `position`. This is then stored in a variable called `new_position`.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 9-10
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+print(position)
+
+new_position = position + key
+print(new_position)
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+**Test:** Click the **Run** button. 
+
+As your `key` is 3, it should add 3 to the `position` and store it in your `new_position` variable.
+
+For example, letter 'e' is at position 4. To encrypt, you add the `key` (3), giving 7.
+
+```
+Please enter a character: e
+4
+7
+```
+
+--- /task ---
+
+--- task ---
+
+What happens when you try and encrypt the letter 'y'?
+
+```
+Please enter a character: y
+24
+27
+```
+
+Notice how the `new_position` is 27, and there aren't 27 letters in the alphabet!
+
+--- /task ---
+
+--- task ---
+
+Use a `%` to tell the new position to go back to position 0 once it gets to position 26.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 9
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+print(position)
+
+new_position = (position + key) % 26
+print(new_position)
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+Finally, print the letter at the new position.
+
+For example, adding the key to the letter 'e' gives 7, and the letter at position 7 of the alphabet is 'h'.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 12-13
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+print(position)
+
+new_position = (position + key) % 26
+print(new_position)
+
+new_character = alphabet[new_position]
+print(new_character)
+--- /code ---
+
+--- /task ---
+
+--- task ---
+
+**Test:** Click the **Run** button. 
+
+Try out your code. 
+
+--- /task ---
+
+--- task ---
+
+Remove some of your print statements, just printing the new character at the end.
+
+--- code ---
+---
+language: python
+filename: main.py
+line_numbers: true
+line_number_start: 1
+line_highlights: 11
+---
+alphabet = 'abcdefghijklmnopqrstuvwxyz'
+key = 3
+
+character = input('Please enter a character: ')
+
+position = alphabet.find(character)
+
+new_position = (position + key) % 26
+
+new_character = alphabet[new_position]
+print('The new character is: ', new_character)
+--- /code ---
+--- /task ---
+
+--- task ---
+
+**Test:** Click the **Run** button and try out your program!
+
+--- /task ---