setting maximum guesses

Learning Goals

By the end of the lesson, students will be able to:

keep track of the state of the game
increment a variable

Overview

Students use their knowledge of defining functions, creating variables, and conditionals to add a maximum number of guesses to their game. If the maximum number of guesses has been exceeded, then the game returns a game over message.

Suggested stations

variable values
conditional syntax

plan (5 minutes)

Lead a discussion with students about how the guessing part of the game would work in the human context. The final solution should look similar to:
- Person 1 thinks of a number. (variables)
- Person 1 decides the maximum number of guesses. (variables)
- If the person has guesses left. (conditionals)
  - Person 2 guesses a number.
  - Person 1 (game) checks if the guess is correct. (conditionals)
    - If the guess is correct person 2 wins (return, strings)
    - Otherwise person 1 give person 2 a hint: higher or lower. (function, return, strings, conditional)
- Otherwise game is over. (conditionals)
Label each of the steps with a javascript concept (in the parentheses above)
Discuss which concepts are new.

produce (20 minutes)

Remind students that their goals are:

Create a variable to store the maximum guesses

Create a function called checkDone that checks if the current number of guesses is greater than or equal to the maximum guesses.

If it is tell the player the game is over.
Otherwise check the guess.

pseudocode:

SET answer to number
SET guesses to 0
SET maxGuesses to number

FUNCTION main (guess)
 RETURN guessNumber(guess)

FUNCTION guessNumber (guess)
 INCREMENT guesses
 IF checkDone() is true
   RETURN lose message
 ELSE
   IF checkGuess(guess) is true
     RETURN win message
   ELSE
     RETURN renderHint(guess)

FUNCTION checkDone (guess)
 IF guesses is greater than or equal to maxGuesses
   RETURN true
 ELSE
   RETURN false

FUNCTION checkGuess (guess)
 IF guess is equal to answer
   RETURN true
 ELSE
   RETURN false

FUNCTION renderHint (guess)
 IF guess is greater than answer
   RETURN too big hint
 ELSE
   RETURN too small hint

With their partner, students plan and attempt to implement a solution for creating a maximum number of guesses. If the maximum number is reached, the game should output 'Game over'

Fill in handout
Discuss plans
Attempt a solution
Justify reasoning

implement (15 minutes)

Discuss with students their ideas. Make sure to have students from each group explain what they attempted or any ideas they had on how they could use their knowledge to implement a solution.

After hearing their solutions, introduce students to the teacher solution.


var MAX_TRIES = 10
var guesses = 0
var answer = 6

function main (guess) {
   return guessNumber(guess)
}

function guessNumber (guess) {
   if (checkDone()) {
     return 'Game over'
   } else {
     if (checkGuess()) {
       return `Correct!`
     } else {
       return renderHint(guess)
     }
   }
}

function checkDone (guess) {
   if (guesses >= MAX_TRIES) {
     return true
   } else {
     return false
   }
}

function checkGuess (guess) {
   if (guess === answer) {
     return true
   } else {
     return false
   }
}

function renderHint (guess) {
   if (guess > answer) {
     return `${guess} is too high!`
   } else {
     return `${guess} is too low!`
   }
}

Students contrast the ideal solutions with their own ideas.
Student implement a working solution in their project.

justify (5 minutes)

As a group, explain the code that they have written. Make sure to decompose each block and expression that was added to the code.
Tell students that in the future, they are expected to justify their code in this way after each feature that they add.
Students practice by explaining their code to a partner.

test

Students play the game of their partner.
When students are testing a game, they are looking for:
- bugs
- feature improvements
When students find a bug they fill out a bug report:
- What were you doing in the game?
- What did you type into the input box?
- What did you expect to happen?
- What actually happened?

maximum guesses