We wanted to discover if carbon dioxide gas affected monarch larvae development and growth. We wanted to discover this because the carbon dioxide levels in the air are increasing, and we wanted to see if increased levels would have a negative affect on organisms in our world. Our results supported our null hypothesis. The carbon dioxide had no affect. We think this is true because the larvae were fed leaves that were grown under normal carbon dioxide levels. Some uncertainties we have about our results are that the carbon dioxide might have harmed the inside of the larvae where we could not measure the affect, some students might not have been careful when dispensing the carbon dioxide or recording their data. Two additional things we learned from this experiment were that the experiment does not always turn out as expected, and how important it is to keep controls in an experiment.