Alot of times kids go through what is called "developmental stuttering." This typically happens when they are learning new sounds and words.  I have personally gone through it with my son a few times over the last couple years.  THe longest it has ever lasted was a little over a month.  One important tip that I learned from a speech therapist is don't interrupt them.  Let them go and let them work it out so the frustration doesn't get worse.  Only if they get REALLY frustrated then assist them in filling in the missing word.

All individuals have a particular capacity for fluent speech.  Certain demands upon us can take a bit away from that capacity.  For example, when a child is going through a period of language growth €“ which happens during the preschool years €“ this may lessen their capacity for fluent speech, and stuttering may and often does occur for a period of time.  If you are concerned regarding your child€™s stuttering, you can speak with a speech pathologist who specializes in stuttering.  Often, if treatment is warranted for a preschooler who stutters, it may be in the form of consultation to the parents.  While parents conversational styles are certainly not a cause of a child€™s dysfluency, there are several things all parents can do to promote a home environment that is conducive to the development of fluent expression.

Parents can slow down their rate of speaking, and, if possible the pace of life in general.  A low-key lifestyle can help reduce the demands on the child€™s capacity for fluent speech.  Parents can avoid interrupting the child, give attention to what their child is saying, and maintain eye contact during both moments of fluent and dysfluent speech.  Don€™t ask the child to repeat herself or to slow down, and don€™t be critical of the child€™s speech.  Strive to make talking and conversation enjoyable and fun, and praise the child€™s communicative efforts.  Focus on what the child is saying rather than how it is said.  What can be very helpful is setting aside a short period of time each day where the child has your undivided attention and you can play and talk in a child-directed manner, where you follow your child€™s lead.  During this time, as always, the parent can model a slower, easy rate of speech, incorporate pauses, and practice appropriate turn-taking skills.