'Thicker Than Water' Star Brooklyn Tankard -- My Kid Went from Truant to Honor Student!

Brooklyn Tankard -- one of the stars of Bravo's "Thicker than Water" -- is proving everyone wrong after she was arrested last year for allowing her kid to skip school ... because the kid is now a scholastic star.

A judge ordered Brooklyn to become a more serious parent, monitoring her daughter's homework and school attendance, and apparently it paid off.

11-year-old Diamond just made the honor roll in her 6th grade class.

It's a big turnaround ... Brooklyn's arrest followed 16 unexcused absences and 35 unexcused tardies. Authorities felt Brooklyn was enabling the kid to become a truant.

She got schooled!