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Aryan: Ok, thanks dear. I have understood, how to create and destroy clones of
the sprites, as per our requirement. But what are these “hide” and “show” blocks
in Figure (5.2 and 5.4)? Please explain this also.

Gowri: Sure.

5.2 SHOW AND HIDE BLOCKS— “LOOKS” BLOCK

5.2.1 “show” block
This is a “stack” block used to show the sprite, when it is required.

5.2.2 “hide” block
This is a “stack” block used to hide the sprite, when it is required.

5.3 RECEIVE AND BROADCAST MESSAGES— “EVENTS” BLOCK
5.3.1 “when I receive…” block

This block is a “hat” block used to do some specific task when the sprite receives the
message, sent by same sprite or any other sprite.

5.3.2 “broadcast…” block
This block is a “stack” block used to broadcast
or send the particular message. This block has

a dropdown list, from where you can choose a
message name or can also create a new message
and give a name for message as per your choice.
(see figure 5.5)
Fig. 5.5
5.3.3 “broadcast… and wait” block

This block is a “stack” block used to broadcast or send a particular message either
an existing one or a new message, and then wait until all scripts triggered by that
message have finished running before continuing.

Gowri: So, in previous coding (figure 5.2 and 5.4), the sprite “planet” is hidden
when “flag” is clicked means when game is started, it is not showing instantly
and same with the missile. It will appear when clone of this sprite is created.

Aryan: Ok, dear Gowri, I have understood it now. Then what is the need to learn
this concept of broadcast and receive message? Could you teach me this block in
detail as well?

Gowri: Yes dear, Sure! When there is a situation, where a sprite is hidden and we need to show
it from another sprite’s script or code, we cannot show this sprite directly. Instead, we need
to broadcast a message, and then show the sprite when it receives that message. Let’s learn
this concept with the help of an activity.

Scratch 49