Scratch

This would be for sprite1:
[blocks]
<when[ space ]key pressed> (or whatever you want to happen)
<broadcast[ shoot
[/blocks]
This would be for the projectile sprite:
[blocks]
<when I receive[ shoot
<go to[ sprite1
<show>
<repeat until> something happens
<move( # )steps>
<end>
<hide>
[/blocks]