Storing:
It is okay to place seed pods in an envelope as you collect them but be sure and spread them in a single out on a tray or screen to dry when you return to the classroom.  Marigold seed heads contain many seeds and hold a lot of moisture.  This cluster of seeds is very susceptible to molding if not given adequate air circulation.  You may place the seed heads in shoe boxes, on trays or in shallow dishes until you are ready to take them apart.  Whatever storage method you use, be sure they remain in single layers.  Another option is to separate the seeds from the shaft right away.  Using this method will reduce drying time. 

After the seeds are fully dried, they can be packaged in the paper seed envelopes, about a dozen to a pack. Store the packs in a dark, cool place. The most important aspects of seed storage is to assure that they are consistently dry and away from severe fluctuations of heat.