This is great for many of the projects but there's a down side to donors choose I wouldn't have realized before taking to some teachers. Anecdote warning: family member works in a public school district where the principal and committees won't even investigate funding requests till the teacher has put something up on donorschoose.
My wife's school strongly suggests that she submit a project every year. If it's funded, good for her and the students in her classroom. It's also good for the school since they can then allocate available funding for infrastructure or larger programmatic support (e.g. ESL, special needs, etc.). It's not that the administrator doesn't want to fund her projects, it's just that her requests sit in a huge pile of unfunded requests and something has to give.
Source: wife is a teacher who has successfully funded projects through donors choose.