posted by natasha .
identify factors which may have influenced the validity and reability of the ovservations.thank for your help.
What observations? Who made them? You seem to be using "buzz words" taken from some particular course or text about preschool teaching. You need to be more specific with your question and explain the context.
"May have influenced" sounds like you are evaluating a specific set of observations. Without knowing exactly what this was, we cannot respond.
However, observations are more valid and reliable if subjects are not aware that they are being observed (e.g., one-way mirror). However, with preschoolers, often they will behave normally after a while, if the observer — even if present in the situation — does not interact with them.
I hope this helps. Thanks for asking.