Class – VIII
Subject: Computer
L-8 Scratch Programming II- Variables, Control,
Actions
A.) Fill in the blanks using the words from the help box:
[tempo , record new sound, commands, volume,
Boolean block, block, variable ]
1) Scratch provides all types of commands as blocks that can be stacked to form a program or script.
2) The loudness of a sound is called its volume, and the speed at which a sound plays is called its tempo.
3) A variable is a
placeholder that can hold / store a value as long as your scripts runs.
4) To record a new sound click on the record a new sound button.
5) The condition is defined via a Boolean block .
B) State ‘T’ for True or ‘F’ False:
1) In scratch, movement of a sprite
draws on stage only if pen is down. FALSE
2) A variable is named storage
location which holds a value as long as the script runs._TRUE
3) Multiple sprites can receive a
message. TRUE
4) You can record a new sound on
Scratch. TRUE
5) Green flag is located at the top
right corner of the stage._ FALSE
C) Multiple Choice Question:
1) Which block menu has the blocks
to show or hide a sprite from the stage?
a) Pen
b) Motion
c) Looks
Ans: c) Looks
2) Which tab is used to add a new
sound on the stage.
a) Music
b) Sounds
c) Costumes
Ans: b) Sounds
3) Which of the following are
conditional block.
a) If-else
b) Repeat
c) Forever
Ans: a) If-else
4) These blocks are repeat, repeat
until, forever.
a) Loop block
b) Stack block
c) Selection block
Ans: a) Loop block
5) The type variable described for
only one sprite.
a) Global
b) Cloud
c) Local
Ans: c) Local
d) Answer the following questions:
1) What are variables in scratch?
Ans: Variables in
Scratch are placeholders that store and hold values. They allow the program to
remember and manipulate data as the script runs.
2) What are the different kinds of variables provided
by the scratch? Explain.
Ans: Scratch
provides two main types of variables:
Local Variables: These are specific to a sprite and can only be used
by that sprite.
Global Variables: These are shared among all sprites in a project.
3) What are Events in scratch? How are these useful.
Ans: Events in
Scratch are actions or occurrences that trigger specific blocks of code.
Examples include the green flag clicked, key pressed, or sprite clicked. Events
make programs interactive and responsive to user actions.
4) Explain the process of adding new sound from the
sound library.
Ans: To add a new
sound from the sound library in Scratch, click on the "Choose a
Sound" button, then select the desired sound from the library. After
selecting, click on the "OK" button to add the sound to the project.
5) What is the difference between if and if-else
block?
Ans: The if block
checks a condition and executes a set of statements if the condition is true.
The if-else block also checks a condition but has an alternative set of
statements to execute if the condition is false.
6) What is the difference between repeat, repeat until
and forever block?
Ans: The repeat block
repeats a set of statements for a specified number of times. The repeat until
block repeats a set of statements until a specified condition becomes true. The
forever block repeats a set of statements indefinitely.
Lab Activity:
1) Open scratch and add any Sprite of your choice on the
stage. Create a script and perform the following activities:
a) Move towards east and then make a circle.
Ans: 1) when green flag clicked
go to x: (-240) y: 0 // Assuming starting point is at the center
of the stage
point in direction 90 // Pointing towards east
repeat 36
move 10 steps
turn 10 degrees
end
b) Speak something on the stage.
Ans: when green flag clicked
say "Hello, Scratch!" for
2 seconds
c) Add some music in your project.
Ans: when green flag clicked
play sound [your_music.mp3] // Replace with the name of your music file
2) Draw a flower in scratch.
Ans: when green flag clicked
repeat 36
// Draw a petal
forward 50
right 45
forward 50
right 135
forward 50
right 45
forward 50
// Move to draw the next petal
right 10
end
3) Write a scratch program to draw this.
Ans: when green flag clicked
// Assuming the desired shape is a
square
repeat 4
forward 100
turn 90 degrees
end
Critical thinking:
1) How to write an interactive program in which a sprite
is crazily drawing on stage forever, but if the user presses spacebar, the pen
size and the pen color change along with a sound play.
Ans: pen size variable
[size]
when
green flag clicked
forever
// Check if space key is pressed
if key [space v] pressed?
// Change pen size and color
set pen size to (size)
set pen color to [random color]
// Play sound
play sound [your_sound.mp3]
end
// Crazily draw on stage
move (10) steps
turn (15) degrees
change size by (1)
end
2) Charvi is playing a game created by her teacher using
Scratch. The game works like this:
An
item/ thing name is shown on screen and then the screen shows moving images of
multiple things/ sprites. The player has to click on correct image / sprite as
per displayed name. If the player clicks on correct sprite / image, a ball
sprite in the right corner starts jumping and clap sound also plays. If the
player wants to move to next thing/ item, the player can press a spacebar.
Ans: when
green flag clicked
forever
// Show item/thing name on screen
say [item_name] for (2) seconds
// Show moving images of multiple
things/sprites
// (Code logic for displaying moving images)
// Wait for player's click
wait until <mouse down?>
// Check if correct sprite/image is clicked
if touching [correct_sprite v]?
// Ball sprite jumps
repeat (3)
jump (20) steps
wait (0.2) seconds
end
// Clap sound plays
play sound [clap.mp3]
end
// Wait for spacebar press to move to the
next thing/item
wait until <key [space v] pressed?>
end
Group
Discussion:
1) Discuss the different methods to add sounds in a
project. Create a loop structure and discuss how to create a pattern and apply
sounds while pressing key.
Draw a
picture based on the above group discussion.
Ans: Discussion Points:
Using
the "play sound" block to add sounds.
Utilizing
the "when key pressed" event for key interactions.
Creating
a loop structure to repeat sound patterns.
Discussing
how to synchronize sound with other actions in the project.
