What's really weird is how different 2008 and 2009 are for "same teacher, different subjects".
In 2008, it looks like a blob (no real trend). In 2009, some teachers obviously learn how to do well in VAM (excelling at both math and english "teaching"), and others don't. I guess that some teachers learnt what it takes to get good VAM scores.
As a (UK, math(s)) teacher I have to warn you that gaming the scores will inevitably happen when you have scores and those scores may impact on career.
In 2008, it looks like a blob (no real trend). In 2009, some teachers obviously learn how to do well in VAM (excelling at both math and english "teaching"), and others don't. I guess that some teachers learnt what it takes to get good VAM scores.