Online courses directory (10)

Explore how we have hidden secret messages through history. What is Cryptography?. Probability Space. The Caesar Cipher. Polyalphabetic Cipher. The One-Time Pad. Frequency Stability. The Enigma Encryption Machine (case study). Perfect Secrecy. Pseudorandom Number Generators.

Solve problems using Mathematics, Computer Science and more!. Introduction. The Discovery. Clue #1. Clue #2. Clue #3. Crypto Checkpoint 1. Clue #4. Checkpoint. Crypto Checkpoint 2. Crypto Checkpoint 3. What's Next?. Introduction. The Discovery. Clue #1. Clue #2. Clue #3. Crypto Checkpoint 1. Clue #4. Checkpoint. Crypto Checkpoint 2. Crypto Checkpoint 3. What's Next?.

How have humans protected their secret messages through history? What has changed today?. What is Cryptography?. Probability Space. The Caesar Cipher. Caesar Cipher Exploration. Frequency Fingerprint Exploration . Polyalphabetic Cipher. Polyalphabetic Exploration. The One-Time Pad. Perfect Secrecy Exploration. Frequency Stability. Coin flip sequences. Frequency Stability Exploration. The Enigma Encryption Machine (case study). Perfect Secrecy. Pseudorandom Number Generators. Random Walk Exploration. Ciphers vs. Codes. Shift Cipher. Caesar cipher encryption. Caesar Cipher Decryption. Caesar cipher frequency analysis. Vigenere cipher encryption. XOR Bitwise Operation. XOR & the One-Time Pad. XOR Exploration. Bitwise Operators. What's Next?. The Fundamental Theorem of Arithmetic. Public Key Cryptography: what is it?. The Discrete Logarithm Problem. Diffie-Hellman Key Exchange. RSA Encryption: step 1. RSA Encryption: step 2. RSA Encryption: step 3. Time Complexity (Exploration). Euler's Totient Function. Euler Totient Exploration. RSA Encryption: step 4. What should we learn next?. What is Modular Arithmetic?. Modulo Operator. Congruence Modulo. Congruence Relation. Equivalence Relations. The Quotient Remainder Theorem. Modular Addition & Subtraction. Modular Addition. Modular Multiplication. Modular Multiplication. Modular Exponentiation. Fast Modular Exponentiation. Fast Modular Exponentiation. Modular Inverses. Introduction. Primality Test Challenge. Trial Division. Level 1: Primality Test. Running Time. Level 2: measuring running time. Computer Memory (space). Binary Memory Exploration. Algorithmic Efficiency. Level 3: Challenge. Sieve of Eratosthenes. Level 4: Sieve of Eratosthenes. Primality Test with Sieve. Level 5: Trial division using sieve. The Prime Number Theorem. Prime density spiral. Prime Gaps. Time Space Tradeoff. Summary (what's next?). Randomized Algorithms (intro). Conditional Probability (Bayes Theorem) Visualized. Guess the coin. Random Primality Test (warm up). Level 9: Trial Divison vs Random Division. Fermat's Little Theorem. Fermat Primality Test. Level 10: Fermat Primality Test. What's Next?. What is Cryptography?. Probability Space. The Caesar Cipher. Caesar Cipher Exploration. Frequency Fingerprint Exploration . Polyalphabetic Cipher. Polyalphabetic Exploration. The One-Time Pad. Perfect Secrecy Exploration. Frequency Stability. Coin flip sequences. Frequency Stability Exploration. The Enigma Encryption Machine (case study). Perfect Secrecy. Pseudorandom Number Generators. Random Walk Exploration. Ciphers vs. Codes. Shift Cipher. Caesar cipher encryption. Caesar Cipher Decryption. Caesar cipher frequency analysis. Vigenere cipher encryption. XOR Bitwise Operation. XOR & the One-Time Pad. XOR Exploration. Bitwise Operators. What's Next?. The Fundamental Theorem of Arithmetic. Public Key Cryptography: what is it?. The Discrete Logarithm Problem. Diffie-Hellman Key Exchange. RSA Encryption: step 1. RSA Encryption: step 2. RSA Encryption: step 3. Time Complexity (Exploration). Euler's Totient Function. Euler Totient Exploration. RSA Encryption: step 4. What should we learn next?. What is Modular Arithmetic?. Modulo Operator. Congruence Modulo. Congruence Relation. Equivalence Relations. The Quotient Remainder Theorem. Modular Addition & Subtraction. Modular Addition. Modular Multiplication. Modular Multiplication. Modular Exponentiation. Fast Modular Exponentiation. Fast Modular Exponentiation. Modular Inverses. Introduction. Primality Test Challenge. Trial Division. Level 1: Primality Test. Running Time. Level 2: measuring running time. Computer Memory (space). Binary Memory Exploration. Algorithmic Efficiency. Level 3: Challenge. Sieve of Eratosthenes. Level 4: Sieve of Eratosthenes. Primality Test with Sieve. Level 5: Trial division using sieve. The Prime Number Theorem. Prime density spiral. Prime Gaps. Time Space Tradeoff. Summary (what's next?). Randomized Algorithms (intro). Conditional Probability (Bayes Theorem) Visualized. Guess the coin. Random Primality Test (warm up). Level 9: Trial Divison vs Random Division. Fermat's Little Theorem. Fermat Primality Test. Level 10: Fermat Primality Test. What's Next?.

We've always been communicating.... as we moved from signal fires, to alphabets & electricity the problems remained the same. What is Information Theory?. Prehistory: Proto-writing. Ptolemaic: Rosetta Stone. Ancient History: The Alphabet. Source Encoding. Visual Telegraphs (case study). Decision Tree Exploration. Electrostatic Telegraphs (case study). The Battery & Electromagnetism. Morse Code & The Information Age. Morse code Exploration. What's Next?. Symbol Rate. Symbol Rate Exploration. Introduction to Channel Capacity. Message Space Exploration. Measuring Information. Galton Board Exploration. Origin of Markov Chains. Markov Chain Exploration. A Mathematical Theory of Communication. Markov Text Exploration. What's Next?. What is Information Theory?. Prehistory: Proto-writing. Ptolemaic: Rosetta Stone. Ancient History: The Alphabet. Source Encoding. Visual Telegraphs (case study). Decision Tree Exploration. Electrostatic Telegraphs (case study). The Battery & Electromagnetism. Morse Code & The Information Age. Morse code Exploration. What's Next?. Symbol Rate. Symbol Rate Exploration. Introduction to Channel Capacity. Message Space Exploration. Measuring Information. Galton Board Exploration. Origin of Markov Chains. Markov Chain Exploration. A Mathematical Theory of Communication. Markov Text Exploration. What's Next?.

20th century solutions to new problems in Cryptography. The Fundamental Theorem of Arithmetic. Public Key Cryptography: what is it?. The Discrete Logarithm Problem. Diffie-Hellman Key Exchange. RSA Encryption: step 1. RSA Encryption: step 2. RSA Encryption: step 3. Euler's Totient Function. RSA Encryption: step 4. What should we learn next?.

Why do Primes make some problems fundamentally hard? Build algorithms to find out!. Primality Test. Running Time. Computer Memory (space). Algorithmic Efficiency. Sieve of Eratosthenes. Primality Test with Sieve. The Prime Number Theorem. Time Space Tradeoff. Conditional Probability Visualized.

GMAT: Data Sufficiency 1. GMAT: Data Sufficiency 2. GMAT: Data Sufficiency 3. GMAT: Data Sufficiency 4. GMAT: Data Sufficiency 5. GMAT: Data Sufficiency 6. GMAT: Data Sufficiency 7. GMAT: Data Sufficiency 8. GMAT: Data Sufficiency 9. GMAT: Data Sufficiency 10. GMAT: Data Sufficiency 11. GMAT: Data Sufficiency 12. GMAT: Data Sufficiency 13. GMAT: Data Sufficiency 14. GMAT: Data Sufficiency 15. GMAT: Data Sufficiency 16. GMAT: Data Sufficiency 17. GMAT: Data Sufficiency 18. GMAT: Data Sufficiency 19. GMAT: Data Sufficiency 20. GMAT: Data Sufficiency 21. GMAT Data Sufficiency 21 (correction). GMAT: Data Sufficiency 22. GMAT: Data Sufficiency 23. GMAT: Data Sufficiency 24. GMAT: Data Sufficiency 25. GMAT: Data Sufficiency 26. GMAT: Data Sufficiency 27. GMAT: Data Sufficiency 28. GMAT: Data Sufficiency 29. GMAT: Data Sufficiency 30. GMAT: Data Sufficiency 31. GMAT: Data Sufficiency 32. GMAT: Data Sufficiency 33. GMAT: Data Sufficiency 34. GMAT: Data Sufficiency 35. GMAT: Data Sufficiency 36. GMAT: Data Sufficiency 37. GMAT: Data Sufficiency 38. GMAT: Data Sufficiency 39. GMAT Data Sufficiency 40. GMAT Data Sufficiency 41.

Khan Academy is collaborating with MIT to develop videos on science and engineering projects. Through the MIT+K12 initiative, MIT students have created videos on hands-on projects, simulations and historic experiments. Enjoy!. Bridge Design and Destruction! (part 1). 2D Equilibrium -- Balancing Games. Shifts in Equilibrium. The Marangoni Effect: How to make a soap propelled boat!. Earth's Tilt 1: The Reason for the Seasons. Earth's Tilt 2: Land of the Midnight Sun. Homeostasis. A Crash Course on Indoor Flying Robots. The Invention of the Battery. The Forces on an Airplane. Flocculation: Making Clean Water. A Voyage to Mars: Bone Loss in Space. Bouncing Droplets: Superhydrophobic and Superhydrophilic Surfaces. Bread Mold Kills Bacteria.

Introduction to programming and computer science. Introduction to Programs Data Types and Variables. Binary Numbers. Python Lists. For Loops in Python. While Loops in Python. Fun with Strings. Writing a Simple Factorial Program. (Python 2). Stepping Through the Factorial Program. Flowchart for the Factorial Program. Python 3 Not Backwards Compatible with Python 2. Defining a Factorial Function. Diagramming What Happens with a Function Call. Recursive Factorial Function. Comparing Iterative and Recursive Factorial Functions. Exercise - Write a Fibonacci Function. Iterative Fibonacci Function Example. Stepping Through Iterative Fibonacci Function. Recursive Fibonacci Example. Stepping Through Recursive Fibonacci Function. Exercise - Write a Sorting Function. Insertion Sort Algorithm. Insertion Sort in Python. Stepping Through Insertion Sort Function. Simpler Insertion Sort Function. Introduction to Programs Data Types and Variables. Binary Numbers. Python Lists. For Loops in Python. While Loops in Python. Fun with Strings. Writing a Simple Factorial Program. (Python 2). Stepping Through the Factorial Program. Flowchart for the Factorial Program. Python 3 Not Backwards Compatible with Python 2. Defining a Factorial Function. Diagramming What Happens with a Function Call. Recursive Factorial Function. Comparing Iterative and Recursive Factorial Functions. Exercise - Write a Fibonacci Function. Iterative Fibonacci Function Example. Stepping Through Iterative Fibonacci Function. Recursive Fibonacci Example. Stepping Through Recursive Fibonacci Function. Exercise - Write a Sorting Function. Insertion Sort Algorithm. Insertion Sort in Python. Stepping Through Insertion Sort Function. Simpler Insertion Sort Function.