I am allowed to use my school's greenhouse and have some space allotted to me. I want to start growing microgreens, but most of the videos and sources I read are always trying to "sell" me something. Is there any reputable site (free to access) that has this information on yielding microgreens or just general microgreen-like plant rearing in a greenhouse environment? I am a bit out of my element since I have not frequented the greenhouse much, and like to prime myself before asking friends / teachers.
If you're googling how to grow microgreens in a greenhouse, you will likely get a lot of sales and information of the type you're complaining about, or information aimed at large professional growers. The other problem you might have is that any 'controlled conditions' mentioned as suitable for this type of crop may not be the same conditions created for growing other people's crops in a shared greenhouse. However, I'm having the same difficulty you're having in finding out what the 'controlled conditions' in a greenhouse might be for microgreens.
Microgreens can be easily grown on a sunny kitchen windowsill or outdoors, and anyone growing in greenhouses is usually a commercial producer, or a small producer growing for sale, so that's why its difficult to find the information you want. Maybe you can adapt the methods in the links below to the greenhouse space you've been allotted:
Note there is a requirement for a minimum of 4 hours filtered sunlight or very bright daylight per day, or artificial gro lights, so the space you've been allocated in the greenhouse needs to be appropriate for this.