Image credit: Greg Hume
Dandelions aren't the most obvious resource for the science classroom. However, dandelion flower stalks (scapes) have a strong gravitropic response, and this practical offers a simple and fun way to look at gravitropism over the course of a double lesson.
Just one of the resources from the excellent SAPS website.
http://www.saps.org.uk/secondary/teaching-resources/677