Catholic Answers says the following:
Concerning human evolution, the Church has a more definite teaching. It allows for the possibility that man’s body developed from previous biological forms, under God’s guidance, but it insists on the special creation of his soul. Pope Pius XII declared that "the teaching authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions . . . take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter—[but] the Catholic faith obliges us to hold that souls are immediately created by God" (Pius XII, Humani Generis 36). So whether the human body was specially created or developed, we are required to hold as a matter of Catholic faith that the human soul is specially created; it did not evolve, and it is not inherited from our parents, as our bodies are.
H. L. Mencken expressed admiration for how Catholics handled the evolution issue:
[The advantage of Catholics] lies in the simple fact that they do not have to decide either for Evolution or against it. Authority has not spoken on the subject; hence it puts no burden upon conscience, and may be discussed realistically and without prejudice.
Pope Pius XII, a deeply conservative man, directly addressed the issue of evolution in a 1950 encyclical,
Humani Generis. The document makes plain the pope’s fervent hope that evolution will prove to be a passing scientific fad, and it attacks those persons who “imprudently and indiscreetly hold that evolution …explains the origin of all things.” Nonetheless, Pius XII states that
nothing in Catholic doctrine is contradicted by a theory that suggests one specie might evolve into another—even if that specie is man.
The Pope declared:
The Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions, on the part of men experiences in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter—for the Catholic faith obliges us to hold that souls are immediately created by God.
In other words, the Pope could live with evolution, so long as the process of “ensouling” humans was left to God (as we just saw was the case in the excerpt from Catholic Answers).
Basically, I don't think they want to be faced with another "Galileo" incident, so they seem to be careful not to take a firm stance one way of the other. My son attended a Catholic HS. He had both religion classes and science classes. His biology class, for instance, taught evolution, and
so did his religious teacher 
(at least he did in his freshman year when they studied the OT), calling the Creation narrative, a "
myth" (which seems to go beyond what the RCC is willing to say or permit at this point).
If I had to guess, I would say that most parochial schools teach standard "public school" evolution to their students with the added qualifier that whatever is true about our origins, God is intimately involved with it.
I'm also sure that Creation is taught, in one manner or another, in their religion classes.
If this is important to you, and you are considering a particular Catholic school for your child,
why not go to the school and see what the curriculum for both their science and religion classes look like. Also, wouldn't this have been a better question to ask in
OBOB?
Yours and His,
David
p.s. - just FYI, much of the above was exerpted from
http://www.catholic.com/tracts/adam-eve-and-evolution AND
http://law2.umkc.edu/faculty/projects/ftrials/conlaw/vaticanview.html
