Grammar Police

Whether it was learned or inherited, for some time now certain members of my family mocked what they believed was unnecessary policing of their speech. Granted, the past two years in the mid-west has all but destroyed the small amount of proper speech left in my brain after conversing with four children, whose regard for the English language compels me to take them with (see what I mean?) next time the grammar rodeo is in town.
Regardless, as to the extent which H knows English, I thought we'd find some insight from her first term report card--where, as proud parents we'll point out that she is 3rd in her class. Her grade in English is solid, she seemed to be doing very well and we assumed she must be learning quite a bit with such high marks and all; that is until we read the ENGLISH teacher's comment "She did good." Oh well, they must be learning the vernacular based on where their adoptive family is. Sigh.