Spots or stripes on the petals serve as nectar guides to direct the bee to the nectar. Citrus blossoms smell more strongly than marigolds. Give an example of a flower that is really lots of tiny flowers grouped into a large attractive unit. All flowers known as composites are actually groups of many tiny flowers, each with its own male and female parts. These clusters of flowers produce many seeds, one from each flower.
Examples are daisies, sunflowers, mums and desert marigolds.
Yes, for example snapdragons, alfalfa, and lupine. Some orchids go to the extreme of false advertising. The amount of nectar a flower produces depends on its pollinator and also factors such as time of day. Or give them a blank copy of Activity Sheet 29 and have them label the parts. The Biology of a Partnership, by F.G. Barth.