I use this sheet towards the end of the photosynthesis and respiration unit. They are not allowed to use any resources...just their mind!! I usually copy it to both sides of the paper. I have them fill out the front side individually at the beginning of class. With partners they glance over each other's sheet and come to a consensus as to which sheet is accurate. Then together they use manipulatives to practice moving around the different components to these equations until they can put them together perfectly (with teacher approval.) Finally, at the end of class, I have them flip the sheet over and rewrite the equations...they typically see a big difference in their success.