So you're saying we were supposed to be clued that
.length would be interpreted by Angular because of "an implicit mention that expressions are accepted by directives"?
I'm sorry, but that's a highly unreasonable expectation for a beginner's course on Angular. In my experience of other Code School courses so far, they've all evaluated explicitly covered material and I've happily followed along, no issues whatsoever.
Others may find this guessing game to be a fun learning experience, but I found this to be no more effective and an unnecessary deviation from Code School's usual teaching pattern. Disagreements are not "aside" when all users are forced to follow this opinionated teaching method to proceed.
Given how many issues I've encountered with this Angular course so far (I'm only on level 2) compared to the other courses I've completed on Code School, this Angular course is really disappointing. I'm not happy.