Hi, I am trying to make a database for a school, to make an automated roster. There are four entities: Teachers: t1-Jones, t2-Smith, t3-Paddington, t4-..... Classes: c1-YearOne, c2-YearTwo, c3-YearThree, c4-..... Subjects: s1-English, s2-Math, s3-Grammar, s4-..... Hours per class per teacher...