Oh dearie! Cellular respiration is a complicated process consisting multiple other processes. These processes are ones you cannot observe--not even with a microscope.
However, there is something related. Try using ferments, such as yeast and different bacteria (you can probably ask your school science teacher or lab technician, the person who sets up the labs, to buy cultures of these bacteria.) Cellular respiration is using oxygen to take energy stored in the form of chemical bonds in the food. Fermentation doesn't use oxygen. Let's say you choose yeast. And you leave it out in the air. And for another one, you expose it to air. And another one, half the time you expose it to air, half the time you don't. In the end, the ferment which is the most acidic is the one with the most fermentation. Because during fermentation, carbon dioxide is produced, and it becomes more and more acidic as there is more carbon dioxide. So you can measure how you fermentation you have with pH paper.
Also, you shouldn't follow my prodecures exactly as it is written. Try finding what you think is the best way for you. Also, you might tweak it a bit--not exposure to oxygen, maybe a different variable--whatever you want! Just have fun doing it!