Multiple 1-ups in World 3-1

[Popper]

In the original Super Mario game,I cant get the multiple 1-ups to work in World 3-1.  Are there some more specific instructions telling how to do it?  I either jump on top of the second koopa and kill it or hit it on the side and it bounces back & wipes me out. I've tried it on 2 or three different steps.  Is there a particular step that works best?.........Thanks....Popper

[Jeff Ehinger]

I don't think there's any trick to it. You just have to land on the shell *exactly* right. Basically, it's just luck.