> It's not trivial for a middle-schooler to make an incubator
You don't actually need an incubator. Bacteria won't grow as fast at room temperature, but for the kind of experiment she was doing that should not be a problem.
Nevertheless, it is actually pretty easy to make an incubator. Google for "homemade bacterial incubator" and you'll find many sites offering instructions. A typical design uses an aquarium tank, an incandescent lamp, a dimmer, and a thermometer. This should be well within the capability of any middle schooler.
If the kid is up for doing a little programming, they could even toss in an Arduino and use a dimmer that can be controlled by it and automate keeping the temperature constant.
The rest of the things needed, like Petri dishes, agar, and such are available from Amazon. There are even kits specifically aimed at people who want to grow bacteria for science fair projects.
Yes you do need an incubator. Bacteria aren't a simple chemical reaction that just runs more slowly at room temperature. Many bacteria that live in your mouth will not grow at all at room temperature.
I'm not saying someone couldn't hack together this experiment. I'm saying a middle-schooler who can walk into a lab and prepare everything in an afternoon under professional supervision is at an advantage compared to a middle-schooler who has to gather all this equipment and knowledge over the course of weeks and months (which will still be inferior from a non-didactic point of view) without the support of their parents when it comes to performing a valid scientific experiment.
Again, let me point out that this is more evidence of just how deeply ingrained the idea that Science is Something You Can't Do is ingrained in the culture.
The physical requirements for science are easy to get. Specific experiments may be hard, but that's a characteristic of the experiments, not "science". The hard part is all in the attitude, learning to look for reasons why you are wrong instead of right. It is not in the physical gear and it's not in following a particular checkbox procedure thoughtlessly. (If I could, I'd remove "The Scientific Process" from the curriculum. It's a misnomer, literally starting from the word "The".) It is a grave failure of the education system that so many people come out of it thinking otherwise.
You're not understanding the argument. Can a person with no instruction and a kazoo and a person with years of training and a Stradivarius both make music? Sure. But the second one is going to win the prize at the county fair.
The county fair does not have the goal of convincing everybody that they can do music, so the metaphor fails.
Science fairs have the goal of showing everybody they can do science. This is the only sensible goal, because as a mechanism for actually doing science they are worthless. If they fail that goal, they are worthless. Once again, this is a place where people confuse the mechanisms for the goals, a problem our society is having a lot of problems with lately. If the science fair is run in a way that extra super hard convinces people you need "real scientists" and lab coats and training and specialized equipment, it is of negative value and the optimal thing to do is just shut it down.
This science fair should be shut down. It is doing harm and no good.
But the argument was that giving someone a kazoo was not enough to get them interested in music, you must also give them a violin and an instructor or they will lose interest.
You don't actually need an incubator. Bacteria won't grow as fast at room temperature, but for the kind of experiment she was doing that should not be a problem.
Nevertheless, it is actually pretty easy to make an incubator. Google for "homemade bacterial incubator" and you'll find many sites offering instructions. A typical design uses an aquarium tank, an incandescent lamp, a dimmer, and a thermometer. This should be well within the capability of any middle schooler.
If the kid is up for doing a little programming, they could even toss in an Arduino and use a dimmer that can be controlled by it and automate keeping the temperature constant.
The rest of the things needed, like Petri dishes, agar, and such are available from Amazon. There are even kits specifically aimed at people who want to grow bacteria for science fair projects.