If you are talking about a "head start" type program, I'd rot in hell before sending my child to one of those places.
They are AWFUL. At least, in my area. They are ridiculously underfunded, so each "classroom" gets 1 person with any type of credentials (generally just a GED or HS diploma with some type of Early childhood experience...which could be as little as a couple classes, or as much as an associates degree, or even a bachelors degree) and then maybe an "assistant" which is generally just another body working for $6/hr. The classrooms are in various places, from actualy public school buildings to nasty, run-down just-this-side-of-condemned buildings they can rent cheaply. The food is atrocious, the toys are crappy and filthy, and the teachers use horrible discipline methods and while they aren't supposed to isolate students in closets or hit them, ...but hey, in a class of 3 year olds, they pretty much do what they want! I've (sadly, in my role as a social worker for the state) seen it.
Now, on the up side, some of the ladies are really great, and try really hard...but the system in general is crap. The "teachers" are ridiculously undertrained, the materials/environment is bad, and we haven't even gotten to the best part.....
The KIDS!!!
i'm gonna sound like a huge ole witch here...but...the kids that go to these schools are, well, by definition, low-income, which is not necesarily an indicator of a poor home-life (lol, i should know, we're super poor here!!!) but in general, most of these kids have about as anti-AP homes as you can get....all families on public assistance(again, not necesarily an indicator if anything..), living in the subsidized housing "ghetto", with mentalities, beliefs, actions, manners, and worldviews WORLDS away from what i want my child to experience. Spanking is almost certainly the norm in 99% of these families, as is poor nutrition, domestic/other violence, drug use, generally poor manners, yelling, etc, and other poverty-class realities. The children tend to behave very poorly in the free preschools here....a lot of it due to the poor parenting they receive at home which manifests as "discipline issues" in the classroom.... My dd would have no idea how to act in that environment....the last time i went to to developmental evaluations for some of the head start students, I was kicked, spit on, had things thrown at me, was cursed at, and the teachers had to physically restrain one child from biting another.
The classrooms here are like little, horrific war zones. It is sad and infuriating (that children could be treated so poorly as to make them act the way they do) and really makes you feel hopeless, and just ...well...let's just say i bowed out of going the last time it was my turn to do developmental exams...I lied and said dd was sick and i couldn't go. It really distresses me to go to those places....
I'm certainly not saying all poor people are drug-dealing, welfare-receiving, violent people...but, at least in my area, that is the reality of a significant part of the poverty-level people, who are mostly the people whose children are going to be qualifying for the free preschool. I am in a city though, one with a super high crime and poverty rate....likely the situation would be very different in the middle of a cornfield rural area in Iowa or something..lol.
After what i've seen go on in these classrooms......no, just...no.