Why Do Sunflowers Follow the Sun?

Description:  This is an excellent phenomenon that can be used in many different units. According to researchers only young sunflowers will follow the Sun. These flowers are following a natural circadian rhythm to receive the most light for photosynthesis. However when they mature the flowers will mainly face east. The reason for this is fairly simple, bees like warm flowers, and the flowers facing the east are the warmest.

Web Resources:  The Mystery Of Why Sunflowers Turn To Follow The Sun — Solved - NPR, Helianthus - Wikipedia