This is a flexible term that can be used for a variety of different learning situations. Co-op, one room schoolhouse, learning pod etc. It signifies a break from the norm of public school. In Nevada, since microschools are not public, and they are not usually formed as private schools, this means they fall under our homeschooling laws- a parent-directed option.
Parents using microschools, co-ops, learning pods etc must file to homeschool. The parent is the legal director of the child’s education, but is choosing to use X, Y or Z to help educate the child. More on filing here.
MicroschoolingNV.org has a lot of great info on up and coming microschools. Be sure to read about what each offers and what each requires. They are all different!