The learner will distribute color coded index cards with the three main types of rocks written on them to be used in class question and answer session.
Is this sentence correct or does it need a comma?
color-coded index cards
to be used in the qustion and answer session in class.
The comma is optional and modern grammarians are apt to omit it. Consider this: do you need a comma for someone to pause and take a breath?
Sra