Waterman is being retried for allegedly conspiring at age 16 with two former boyfriends to kill her mother, Lauri Waterman, whose body was found inside her burned minivan on Prince of Wales Island in November 2004.
John Westfall, a teacher at Craig High School, says Rachelle Waterman was in his physical education class the morning after her mother was reported missing.
In testimony Tuesday, Westfall said he asked Waterman if she was OK and she said she was fine. Westfall says the girl told him her mother probably got drunk and "ran off the road" somewhere.
Jason Arrant and Brian Radel, expected to testify this week, have pleaded guilty to first-degree murder and are serving long prison sentences.