7,3A Explain the vocabulary items which students may have problems. Remind the students that gross is a unit of quantity equivalent to 12 dozen in this context(i.e. 144 ). Then students look at the various documents before they begin to fill in the invoice7.3 A Explain the vocabulary items which students may have problems. Remind the students that gross is a unit of quantity equivalent to 12 dozen in this context (i.e. 144). Then students look at the various documents before they begin to fill in the invoice