Mr. Mcgregor’s Garden, Peter Rabbit, & The Plant-tastic World of Photosynthesis
This is a well presented guide to a series of lessons introducing plant biology to young school-children. Familiar story-book characters are used and the children are given problems to investigate.
Elsewhere on the site there are links to curriculum units by Fellows of the Yale-New Haven Teachers Institute. Highly recommended as inspiration/starting points for teachers (unless your school is so bowed down by the demands of the National Curriculum that cross-curricular education based on a topic is now a thing of the past).