Bees collect pollen, to feed growing bees in the hive. Pollen can be different colours, to attract bees. Once students know that the pollen is on the anthers of a flower, give them magnifiers to find it, look at it closely, and find out what colour it is. (Tulips have black pollen. Orange lilies purchased in florists have red-brown pollen. Fireweed has green pollen.) Give them pipe cleaners to gently touch the anthers to pick up pollen.
With McBride Elementary, the tulips were not open at Van Dusen, so we used lilies that I had purchased to collect pollen.
Van Dusen Botanical Garden Fantastic Flowers class