Those sentence skipped subject. So it is not sure...
아이들 키가 걱정 돼서 그런 줄 알았죠
I thout it was because you(or someone) worried about kids' height
그날 밤 10시가 되어도 중학생 아이들 방에 불이 꺼지지 않자 출동을 하더군여
Someone moved as the light was on until 10 PM at middle school students' room.