This site provides multiple activities that involve how plants grow. Students can observe different types of seeds from different foods they eat and can see each of the different growth stages the seeds go through. This would be perfect for a science lesson
A bean plant like the picture can be put in the classroom so the students can see how water along with other things help plants grow. This is a good way for students to see the many uses of water as a natural resource. This could also lead into a lesson about plants.