Class V Lesson3 Advanced Scratch

Class V – Lesson3 – Advanced Scratch

Tejas and Jyoti are planning to write a scratch game called “Logic Bingo”. They start discussing the same with Moz. Moz: Why do you call it “Logic Bingo”? Jyoti: In the game there are some conditions. The players have to find out these conditions using logical reasoning. There are only four chances to win the game. We named the game “Logic Bingo”. Moz: So what is this game? Tejas: For sports day in our school, each student can participate in two games from a list of 6 games.

Team games Individual participation games Foot ball Athelitics Basket ball Swimming Kho kho Gymnastics

Jyoti: Rules for combinations of games are as follows:

 Participation in two team games is invalid.  Participation in two individual participation games is valid.  A team game participation and an individual participation game is valid.

Tejas: We want to convert this into a scratch project. In this project students have to find the correct combination of games, that can be played on sports day, in 4 chances. Jyoti: We will not reveal the valid and invalid combinations to students. We display the names of the games. Moz: Good project. So how do you start? Jyoti: The main steps in our project are:

Step 1: Display the games. Step 2: Repeat the following sequence four times. i. Ask the student to enter the first game. Recieve the answer. ii. Ask the student to enter the second game. Recieve the answer. iii. Compare the two games. iv. Display whether the combination is valid or invalid. v. Keep score of valid combinations. Step 3: Display the final score.

Tejas: In the second step we do not know the instructions for i, ii, iii, and v. We want to explore these first. Moz: That is a good idea. Ok start with the first one (i). This is called recieving input from the keyboard.

Recieving input from the keyboard.

Moz: Which block do you find instructions to sense a mouse click ? Tejas: (thinks): Sensing. Oh! So words entered using the keyboard is “sense the keyboard input” . Isn't it? Moz: Correct. Jyoti: Let us check Sensing. (points to ask ): Look at these instructions. Moz: To find out how to use this instruction right click on the instruction to get help. Tejas right clicks on the instruction and gets help for the instruction ask.

Info: To find out about the functionality of an instruction right click on the instruction. This gives you a help option. Help option displays how to use the instruction and an example.

Moz: Build a small block using the instructions and execute.

Example ask block and its execution steps

Tejas: This is good. We can ask a question and also capture the answer entered. Jyoti: Let us enter another question.

Creation of Variables

Tejas: The input entered for the first question is lost. Jyoti: I wish the computer can save the answer somewhere. Moz: Sure it can. So what do you need? How do you solve such a problem in Maths? Tejas: In maths we solve such problems using a variable. Moz: Correct. The same logic is used in computers too. Check out the variables block.

Tejas and Jyoti create variables name and age.

Assigning values to a variable Jyoti: Can we store a word in this variable? Moz: Yes. When a word is saved in a variable, the variable is called a string variable. Letters, words or sentences are called strings in Computer language. Jyoti: I want to save answer in the string variable name. Moz: Check out the help for answer.

Moz: The instruction set allows you to save answer in a variable that you already created.

Variable operators Jyoti: Suppose the name typed is “Tejas” then I want to say “Hello Tejas”. How do I get this? Moz: That means you want to join two words and display it. Join is a string operator. Check out these instructions in Operators. Jyoti checks help for string operator join and adds the instruction to the scratch block and executes.

Script of sprite Stage after execution of block

Tejas: How do we compare strings? We will need it for our project. Moz: When you want to compare if two numbers are equal how do you check? For example: The lengths of three sides of a triangle are given. How will you determine if it is an isosceles triangle? Jyoti: We have to compare the lengths as follows. If AB = BC or AB = CA then the triangle is called an isosceles triangle as two sides are equal. Moz: So what is the operator that you used to compare? Jyoti: '='. Moz: You can compare strings for equality just like numbers. Where do you find the comparison instruction? Tejas: In Control block. Tejas and Jyoti write the following blocks to see how operators and control statements can be used.

Script of basketball sprite

Script of Cat sprite Stage after execution of program Moz: Good. Explore the other string operators too. You may get some other ideas of comparison. Tejas and Jyoti explore the following string operators:

======Logic bingo by Tejas: Six sprites for the 6 games. Cat sprite to ask a question and capture the response.

Tejas: The game has a referee of the game who keeps asking questions and displays messages at each stage of the game. Player is the one who plays the game of Logic Bingo. Moz: Good. Have you decided on the variables that you will require for the game? Jyoti: Since the player enters two games of his or her choice to save the names of games, we need two variables, game1 and game2. Moz: Good. What else do you need? Tejas: We can decide if a game is valid or invalid by comparing the types of games. So each time the player enters a choice we should save the type of the game. Later on we can do the comparison and decide if the choices are valid or invalid. So we need two variables, team and individual. Moz: Good. So next what do you do? Tejas: Import the sprites and position them on the stage. Usha: Importing pic here Jyoti: We have to also create the variables. Usha: Variable creating pic here. Moz: Good. Summarize the steps. In a box: Import sprites and position on stage: Select sprites from the available sprites or paint the sprites required for the game. Six sprites for six games and cat sprite as referee of the game. One sprite which has instructions of the game. Create the required variables: Four variables are required. Two to save the names of games and two for the types of games. Moz: What is the next step? How does the program start? Jyoti: Following is the start of the program.

In a box: How does the game start? 1. Start the program 2. Hide the sprites and provide the instructions of playing the game. 3. Hide the instructions and show the sprites.

Moz: How do you take responses from the player? Tejas: Referee asks a question. Aditya responds. The response is saved in game1. Jyoti: We have to also save the type of game. We can use broadcast. Moz sprite can broadcast the name of the game. Then the corresponding game sprite will recieve and save the type of game in choice1. Moz: Very good logic Jyoti. Tejas: If the choice of game is team game, then choice1 = team and if the choice is individual type of game then choice1 = individual. Moz: Good. Jyoti: We can use the same sequence and logic for the second choice of game too. Moz: Correct. Go ahead and build the blocks for referee and game sprites.

In a box: Cat sprite block: Referee gives an instruction “Enter the name of the game you want to play on sports day” Player responds by entering the name of the game. Save the name of the game in the variable game1. Broadcast game1. Game sprite blocks: The game that has been chosen recieves the broadcast. Type of game is also saved by the sprite. Type of game is broadcast to referee sprite. Cat Sprite: recieves the broadcast and says the type of game so that the player knows type of game1.

Referee sprite scripts for Stage of the player for choice1 of the game Logic Bingo choice1 Individual game sprite script to if choice1 is Team game sprite scripts if choice1 is football swimming

Moz: Now that you have one choice, what should be your logic for the next one? Tejas: The block for referee sprite to ask and recieve the response for choic2 will be the same as for choice2, excepting that response of player will be saved in variable game2. The broadcast message too will be different for each choice of game to distinguish from choice1.

Referee sprite scripts for choice2 Stage of the player for choice2 response Jyoti: Now we have to build the logic of comparing choice1 and choice2.

In a box: 1. When choice2 = individual type of game If Choice1 = team game then valid. If Choice1 is another individual game then valid. So when choice2 is individual game: Individual game sprite simply broadcasts correct to referee sprite. No need of any comparison instructions. 2. When choice2 = team If choice1 = individual then Team game sprite broadcasts correct to referee sprite. If choice1 = team then Team game sprite broadcasts wrong to referee sprite.

Team game sprite scripts if choice2 is football Individual game sprite scripts if choice2 is swimming

Moz: What would the referee sprite do now? Tejas: Referee sprite simply says valid or invalid as per the signal that it recieves. Moz: Good. Suppose someone enters their choice1 again in choice2? Jyoti: We can handle that easily. Each of the games sprites can compare with game1 and if it is same a broadcast “duplicate” can be sent to referee sprite. Then the referee sprite can give an appropriate message. Moz: Good. Go ahead and complete the game. I would like to play this game.

Referee sprite scripts to display valid, invalid or Final stage of the game Logic Bingo duplicate choices