I tried out the site that is the subject of the OP (Knack for Teachers). I heartily agree with the sentiments of the OP. The problem wasn't the customer base,

I tried out the site that is the subject of the OP (Knack for Teachers). I heartily agree with the sentiments of the OP. The problem wasn't the customer base, the problem was the product itself. In a word, it sucked. (Okay, two words). The product looks and behaves like an alpha. The UI is counter-intuitive and unpolished. It takes way too much effort just to enter a single student's grade for a single assignment. This service actually makes a teachers' administrative burden worse, especially compared to using the gold-standard Excel spreadsheet. Speaking of Excel...where were the export options? This product doesn't do enough, or execute well enough, to justify being a paid product. (The demo video is the only truly polished thing on the entire site.) Hell, it isn't compelling even as a free offering. Expecting teachers to pay for it was wishful thinking at best. This failed startup isn't useful as a data point for other startups seeking to enter the education technology market, except maybe as an example that execution matters if you've got competition.