Ahh, the infamous sticky spikes. There is a solution on RPS, but it is referenced as an earlier version when it was not level 12, nothing has changed in the level itself though.

@kev:
It might be a good idea to put in a level which is specifically designed to teach people about the concepts which seem to cause a problem for people in this level, namely weight of 1 doesn't cause breakable blocks to break and more importantly (as I think this is the part that really stumps people here) that you can detach putty to make smaller putty blobs. I think because this is really one of the only times that the concept is used (and it comes almost immediately after the putty merging) that people aren't really getting it.

Kev: There is a level that teaches both detach and crumbling blocks on the first row (if you ask frank for help that is). Saying that it's a balancing act between making it easy to understand but challenging. Most people seem to be getting there in the end - and the normal "doh! thats so obvious when I see it" is a good sign I think.