Task: Open the Khan Academy App, Select the Cryptography textbook and read the chapters of the textbook.
Steps:
Open the Khan Academy App 
Select the Cryptography Textbook 
Swipe up the screen to see the chapters 
Click on the Ciphers vs. codes topic 
Swipe up to read the chapter of the textbooks 
Swipe up to read the chapter of the textbooks 
Swipe up to read the chapter of the textbooks