Before we talk about photosynthesis in general biology, I throw the photosynthesis equation at the students and make them interpret it (in a guided manner). Attached is the instruction sheet that I give the students to help walk them through understanding the parts of the equation and starting to think about the parts of the plant that utilize each input. Students make a big poster with groups (my students are grouped in 4's) following the instructions on the sheet.
My students come in with basically no chemistry background, so I also use this as an intro to seeing how equations are balanced (they don't balance it themselves, but quickly realize that the amount of matter on each side is equal), understanding inputs/outputs (NGSS terminology that fits nicely with future modeling activities you may use), identifying atoms and molecules, and just learning how to interpret "scary" information that's not so scary after all!
A couple days later, before we talk about cellular respiration in general biology (and after we do photosynthesis), I throw the cellular respiration equation at the students and make them work with the information as they did with the photosynthesis equation. I lead them to determine the inputs and outputs, count the number of atoms on each side of the equation, and draw a person AND a plant to mark how the inputs get in to each organism and how the outputs get out. They are also forced to think about how cell respiration connects to photosynthesis (the goal is to get them to see that the two equations are reverses of each other). Students make a big poster with groups (my students are grouped in 4's) following the instructions on the sheet.
These lessons are meant to be done on two separate days. Expect each to take students 20-30 minutes. I love these posters because they help students discover things on their own--so much better than lecture!!