Si un niño está cogiendo varios trozos de cartón y los está partiendo en trozos, ¿Cómo le podríamos decir: "no vas a dejar ningún trozo de cartón sin romper"?

You´re not gonna leave any cardboard piece unbroken? / untouched? / intact? / unscratched?

Saludos.

 

Are you going to tear up every last piece of cardboard?

 

I like aztlaniano's translation, but to address your exact question, we "tear" or "rip" cardboard. Only brittle things can be broken, in general (well, lots of exceptions). So I'd say "You're not going to leave a single piece of cardboard untorn / unripped / intact / unshredded?"

That said, I still prefer azt's version.