Turn off your cell phone. Give the teacher your undivided attention for this all too brief meeting. You want to come across as a concerned, involved parent and work or friends on your cell phone can wait until after your parent-teacher meeting.
Ask questions about how instruction is being given. If your young child id doing poorly in an area of instruction say hand-writing, make sure the teacher is doing all they can to reach your child. For example, some children do not respond well to flat paper and pencil. Someone who can't write well on a paper tests or even write their name for preschoolers, may respond tactically to other mediums. One boy who had difficulty writing his name on paper could trace the whole alphabet in the sand out on the play yard. He was a tactile learner. It's not out of the teacher's job description to reach further and teach each child however they can. Make sure your teacher is doing all she can to instruct your child.
Keep asking questions if you feel your child is being scored improperly. For Example, if your older child is doing poorly learning the states and capitals, ask how it's being taught. There is always the child who is a musical learner and when put to a song, they can memorize it exactly. Just because your child doesn't respond or do well or written tests doesn't mean they don't know the information being asked for. It's all a matter of learning styles.
If your child is having exceptional trouble in a certain area an Individualized Educational Plan (IEP) may be suggested. This is a good idea because it really focuses in on problem areas and sets specific goals for the school year. Specifics like "will improve 20% in reading comprehension" are noted and the teacher is obliged to reach these goals with your child.
The suggestion of medication may be mentioned if your child is seen as a disruption to the classroom setting. Do this as a last resort and only after thorough outside testing by a child psychologist. The label Attention Deficit Hyperactivity Disorder (ADHD) is too easily thrown around and Ritalin or other medication is over-prescribed for child that just need specific attention and instruction. The answer is not to medicate the classroom.