Science Buddies: "Ask an Expert"

Hello,
Firstly, thank you for taking time to answer my question Now, I'm preparing to conduct the experiment on the Science Buddies site linked. On the materials list they have 10mL tubes OR bags of the cultures. However, on the site they say to buy them from the amount is completely different. If you get the test tubes with 10mL cultures, you receive 30 sets($45). If you get the bags, you only receive 8 sets($25). While it is a better deal to get the test tubes, if I am going to end up with many extra, it is not worth the extra $20. So, my question is: how many sets of 10mL cultures will I need as a minimum for this experiment to work? https://www.sciencebuddies.org/science- ... p033.shtml

In the end, it basically depends on how many replicates you want to do. If you are following the guide closely it gives you three different conditions: dark, light, and light/dark. You'll need to do more than one tube at each condition so that you know your results aren't due to something being different about that one tube, as opposed to the lighting conditions. I generally would not do less than 3 replicates per condition, but you may choose to do more. You can be more confident in your conclusions when you do more replicates, but the final decision has to be yours as the investigator.

Hope this helps!