Intro CS – Probability and Random Numbers Lesson Plan 6a

Goals  Students can explain random numbers and how computers can generate them  Students can generate random numbers  Students can use the computer to simulate random number experiments to observe probability statistics  Students can predict probability statistics for a given problem  Students can express probability as ratios, decimals, and percentages  Students can write code to generate probability statistics as ratios, decimals, and percentages

Objectives  Students are introduced to random number generation by computers and how they can be used to simulate chance  Students are given real probability problems to code and solve  Results are demonstrated through predications, demos of running code, and displayed results

Pre Requisites  Knowledge of IF blocks, Loops (to simulate mutiple trials), variables (to capture results)  Basic Understanding of BYOB

Materials  Slides with examples (or present on whiteboard)  PCs with Chrome browser to access Snap web site

Lesson Description  Students learn about random number generation in computers, and how it can be used simulate probability experiments  Students practice and extend examples  Students solve probability problems using code and the computer  Students analyze their and others’ solutions, and collaborate towards shared solutions

Lesson Procedure  Warm-up: Define/research what probability is, with an example. Research an example of how random numbers are used with computers to simulate chance  Quick review of IF block, Variables, and Loops  Introduce PICK RANDOM through student investigation and observation of sample work  Give exercises for in class practice  Walk the room answering questions, looking over the shoulder, asking questions, etc.  Check off solutions for completeness and accuracy  Review

Closure/Conclusion  Summary  Random numbers are a powerful way to simulate real world problems and introduce random behaviors into normally predictable code  Future thinking: Discuss Monte Carlo simulations as they relate to Finance, Airplane Boarding Optimization, Sporting Event Results  Ask questions on what is confusing or needs more time/practice

Random Numbers Lesson 5

Warm-up 0 Research/define probability, with a real-life example 0 Research another example of how computers are used to simulate chance

Review: IF blocks  What are IF Blocks?  IF blocks are used to help make decisions and branch your code.  When the IF Block statement is true, whatever is contained inside the decision block is done  Other blocks that use logic: IF/ELSE, Repeat Until, Wait Until

Review: Variables 0 Variables are places we can store results/values 0 Variables can be changed any time 0 Variables can be incremented by one to count things

Review: Loops 0 Used to repeat things a few to many, many times 0 Can repeat: 0 Forever (FOREVER block) 0 A specific number of times (REPEAT 10 block) 0 Until a test is True (REPEAT UNTIL block)

Generating Random Numbers 0 Usually, computers are very predictable will also equal 8 for a computer 0 Spell checking, etc. 0 Sometimes we want computers to simulate life by being less predictable 0 We can use Random Numbers to: 0 Simulate chance (rolling dice, unpredictable events, etc.) 0 Track results in variables 0 Run thousands/millions of simulations very fast 0 We use the Pick Random block (on the green tab)

Investigation 0 Pair up. If you get stuck, ask another pair. 0 Simulate the following by having a sprite Say: 0 the result of rolling one six-sided die 0 the result of rolling two, three, four, or five six-sided dice 0 the result of rolling one ten-sided die 0 the result of picking a random card from a deck 0 sprite must say "Ace of Clubs", "6 of Hearts", etc. 0 Hint: use Join block on green tab to put words/numbers together, and IF blocks

When to use Pick random 0 When you want to simulate chance: 0 50/ /1 0 When you want to wait a random amount of time 0 Wait (pick random 6 to 10) 0 When you want to pick a random thing from a list of things 0 Picking a word in Hangman (future project in class) 0 When you want to make game behavior unpredictable 0 Sometimes go left, sometimes right, etc.

Coding problem 0 Write the following programs: 0 Computer rolls 2 dice, calculate the probability of each roll (2-12) 0 Use the computer to roll 5 dice to play Yahtzee 0 Roll dice, pick all/some/none to keep, repeat 3 times 0 Mark (on paper, write code), to track which scores to take after 3 roles 0 Repeat until can't play, or all categories filled

Review 0 You’ve just learned the basics of random numbers and using computers to measure probability 0 Simulate chance 0 Experiment to calculate results 0 Future thinking: Monte Carlo calculations 0 Finance: predict retirement outcomes 0 Sports: predict team scores 0 Airplane boarding optimization: predict and test models