Rarely. Let's be honest here, most teachers are not even teaching, not to mention sparking anything. They're just (slightly) glorified babysitters maintaining a space where people store their kids during the day (vide http://www.paulgraham.com/nerds.html) with some supposed benefit to the kids and society at large but the results are so hard to quantify that no really knows.
You're an outlier in your field. Which is also probably why there is no popular site like HN for educators -- there are too few of you who really care, not in theory, not in declaration but in the constant effort to improve their process and results. I'm not blaming them, there are no incentives, no feedback loop, and almost no leaders to imitate.