I have always found plants to be an interesting topic because I've seen some schools who go into lots of detail about them and others who cover just the basics. At the middle school level, I have usually taught about plants in the contexts of cells and photosynthesis. No matter what you teach in reference to plants Scholastic has some interactive activities that might fit well into your classroom. There are 11 activities to help students understand roots and stems, photosynthesis, gymnosperms, angiosperms, plants with seeds, plants without seeds, plant cells, plant adaptations, and more.
Each interactive includes a short video, a sing-along, and an interactive quiz. I like that you can pick and choose which activities you want to use and be used as a whole class, at stations or as a homework assignment.
What topics around plants do you teach??